Chapter XIV: Part IV: is on Sigillaria and Stigmaria, the "Sigillaria" (2)

That bacteria are not an inevitable element in potable water is proved by their absence from that of deep springs. They are arrested by filtration through the earth's crust. In any river system they are comparatively fewer towards the watershed, and more frequent towards the mouth. The obvious conclusion is that they are derived from the drainage of the land. As it is known that the bacteria of cholera and typhoid are water-borne, it becomes a problem of vital importance to ascertain if river water is a possible means of distributing these diseases. Ward set to work to ascertain: (i) What was the actual bacterial flora of Thames water; (ii) if this included any pathogenic organisms; (iii) if not, what became of them? The labour required by the first two branches of the enquiry was enormous; he identified and cultivated some eighty species; the resulting answer to the second was happily in the negative.

As to the third, two facts were known. First, that river water, if stored, largely cleared itself of bacteria by mere subsidence; secondly, that Downes and Blunt, in a classical paper communicated to the Royal Society in 1877, had shown that exposure to direct sunlight is fatal to bacteria in a fluid medium. Ward showed that subsidence could not be entirely relied on, as the sediment might easily become the source of re-infection. The effect of sunlight required more critical examination.

It was known that the spores of anthrax were liable to be washed into rivers. Ward determined to study this as the most extreme type of pathogenic infection. As it is undoubtedly the most deadly micro-organism known, and Ward proposed to deal with it on a large scale, it implied no small degree of courage. He found that the spores of anthrax were effectually killed by a few hours' exposure to even the reflected light of a low winter sun. It was clear that this was due to the direct action of the light and not to any heating effect, apart from the fact that they will tolerate boiling for a few minutes. It was further shown that there was no foundation for the theory of Roux and Duclaux that their death was due to poisoning by products of oxidation of the food-medium. Proof of this, indeed, was hardly required, for Pasteur had shown that the bacteria floating in the atmosphere are mostly dead. Were it not so, no surgical operation would be possible. To the bactericidal effect of sunlight is equally to be attributed the absence of bacteria from the High Alps.

The next point was to ascertain to what rays the effect was due. The spores of anthrax are so minute that, when mixed in large numbers with gelatine, they do not affect its transparency, A plate of glass coated with the mixture is at first clear, but ceases to be so if kept in the dark, owing to the germination of the spores. Ward found, in fact, that a photograph could be printed with it, the darkening being the reverse of that of a silver plate. After experiments with coloured screens he completely solved the problem in 1893, with the aid of apparatus supplied by Sir Oliver Lodge and some advice from Sir Gabriel Stokes, by photographing the spectrum on such a plate. It was at once seen that the destructive effect was due to rays of high refrangibility, and, what was extremely important, extended to, and found its maximum in, the ultra-violet. The same results were obtained with the typhoid bacillus. He made the suggestion that the arc light might be used for the disinfection of hospitals and railway carriages.

Comparatively little was known of the life history of any Schizomycete. Ward therefore made a detailed and exhaustive study of that of _Bacillus ramosus_, the _Wurzel bacillus_ of German authors, which is common in Thames water, and bears a superficial resemblance to the anthrax bacillus, but is innocuous. It proved convenient for study, as it ran through its entire life history in from thirty to sixty hours at ordinary temperature. It forms long filaments, the growth of which Ward was able to measure under the microscope with great precision. On plotting out his measurements he obtained a regular curve, from which he found that, under constant conditions, the filament doubled itself in equal times. This he called "the law of doubling." It is the same as the so-called "law of compound interest," and leads to the expression of the growing quantity as an exponential function of the time, so that the time is proportional to the logarithm of that quantity. This relation has, of course, long been familiar in chemical reactions, but, as far as I know, Ward was the first to detect it in any vital process in a plant. This, which was in 1895, has, I think, been overlooked. Stefanowska has since, in 1904, obtained a logarithmic curve for the early period of the growth of maize, which doubles its weight every ten days, and the subject has since been pursued by Chodat and others.

In speculating on the cause of the destructive action of light on bacteria, Ward adopted the view of his friend Elfving, that it inhibited metabolic processes necessary to nutrition. He suggests that the "constructed metabolites" at the moment of assimilation are in a highly unstable condition, and liable to destruction by oxidation promoted by light. He points to the fact that plant structures are frequently provided with colour screens, which would cut off the blue-violet rays and check their action in promoting the rapid oxidation of reserve materials, and he quotes the suggestion of Elfving that chlorophyll itself may serve as such a screen against "destructive metabolic action in synthesis." Ward seems to have attributed little importance to the fact that substantially the same view had long before been put forward by Pringsheim, though received with little favour. His own view that when red and orange predominate in the screens their effect is protective, has since afforded a probable explanation of the colouration of young foliage, especially in the tropics.

It can hardly be doubted that the upshot of Ward's laborious investigations has had a powerful influence in deciding the policy of the future water supply of London. If we hear nothing now of obtaining it from Wales, it is because we know that even polluted flood-water if exposed in large reservoirs will rid itself of its bacterial contamination, partly, as was known already, by subsidence, but most effectually, as shown by Ward, by the destruction of its most deleterious constituents by the direct action of sunlight.

In 1895, Ward was called to the Chair of Botany at Cambridge. He was supported by a distinguished body of fellow-workers, and developed a flourishing school, in which every branch of the science found its scope. The University erected for it an institute which is probably the best equipped in the country, and in March, 1904, I had the pleasure of seeing Ward receive the King and Queen at its inauguration.

During the later years of Ward's life he returned to the study of the Uredineae. The scourge of wheat perhaps from the dawn of agriculture has been "Rust,"

"Ut mala culmos esset rubigo ... intereunt segetes";

and the loss inflicted by it throughout the world is probably not calculable. But the history of the Ceylon coffee disease is only too patent an instance of the injury a uredine can effect.

Eriksson, the most recent authority on the subject, had found himself quite unable to account for sudden outbursts of rust which it did not seem possible to attribute to the result of infection. In 1897 he launched his celebrated theory of the Mycoplasm. He supposed that a cereal subject to rust was permanently diseased and always had been; that the protoplasm of the Uredo-parasite and of the cereal, though discrete, were intermingled and were continuously propagated together; but that while that of the latter was continuously active, that of the former might be latent till called into activity by conditions which favoured it. Ward discussed the theory in his British Association address at Toronto, and was evidently a good deal impressed with it, but nothing short of actual demonstration ever convinced him; and when he proceeded to investigate the actual histological facts on which the theory rested he promptly exploded it.

It is interesting to note that Ward, as I know from correspondence at the time, had himself been embarrassed in investigating the Ceylon coffee disease by the same kind of appearance which had misled Eriksson. It is due to an optical fallacy. When the hypha of a uredine attacks a cell it is unable to perforate it with its whole diameter. It infects it, however, with a reduced and slender filament; this expands again after perforation into a rounded body, the haustorium. In a tangential section the perforating filament cannot be distinguished, and the haustorium looks like an independent body immersed in the cell-protoplasm and with no external connection. It requires a fortunate normal section to reveal what has really taken place. Ward was accordingly able, in a paper in the _Phil. Trans._ in 1903, to dispose conclusively of the mycoplasm. This cleared the ground of an untenable hypothesis. The complicated nature of the problem which still presented itself for investigation can only be briefly indicated. Sir Joseph Banks, whose scientific instinct was sound but curiously inarticulate, had pointed out that the spores entered the stomata, and warned farmers against using rusted litter. Henslow, one of Ward's predecessors in the Cambridge chair, had been confirmed by Tulasne in showing that the uredo-and puccinia-spores (of the barberry) belonged to the same fungus. De Bary traced the germination of the spores and the mode in which the hyphae invaded the host; the fundamental fact, which he observed but did not explain, was that the germinal filament, after growing for a time superficially, bent down to enter the tissues of its host. Pfeffer in 1883 discovered chemotaxis, the directive action of chemical substances on the movement of mobile organisms. De Bary had previously hinted that the hypha might be attracted by some chemical ingredient of the host plant. Myoshi, a pupil of Pfeffer's, showed finally in 1894 that if a plant were injected by a chemotropic substance a fungus-hypha not ordinarily parasitic might be made to behave as such and attack it.

In such circumstances it might seem that the host was not merely incapable of resisting invasion by the parasite but actually invited its attack. Nature is, however, not easily baffled in the struggle for existence. Attack provokes new methods of defence. Ward soon found himself face to face with "problems of great complexity," and these occupied the closing years of his life.

It had been ascertained in fact that the rust fungus is not, as was at first supposed, a single organism, but comprises, according to Eriksson, thirteen distinct species, each with physiological varieties, and that those which are destructive to some grasses and cereals, are incapable of attacking others. This necessitated a scrutiny of the nature of grass-immunity. In a paper communicated to the Cambridge Philosophical Society in 1902, Ward announced a conclusion which was as important as it was unexpected. He had more and more made use of the graphical method for presenting to the eye at a glance the result of a mass of separate observations. In this case he uses it with striking effect. He shows conclusively, as far as rust in brome-grasses is concerned, that: "The capacity for infection, or for resistance to infection, is independent of the anatomical structure of the leaf, and must depend on some other internal factor or factors in the plant."

Finally, he is led to the conclusion that "it is in the domain of the invisible biological properties of the living cell that we must expect the phenomena to reside." He pointed out the probability that light would be thrown on this from the action of chemotaxis, on the one hand, and from that of toxins and antitoxins in animal organisms on the other. This is a most fertile conception, which would, however, have required a good deal of verification, and this, unhappily, he did not live to attempt. But with characteristic ingenuity he pointed out the analogy between the infective capacity of uredospores and the prepotency of pollen, which had previously engaged the attention of Darwin. In a paper published in the following year in the Berlin _Annales Mycologici_, he announced a no less significant result. With his usual thoroughness in research he had cultivated side by side at Cambridge more than two hundred species and varieties of Bromus, and had watched the degree to which they were infected by rust under identical conditions. He found that though in the brome-grasses the rust peculiar to them is specifically identical its _forms_ are highly specialised. The form which attacks the species of one group will not attack those of another. Host and parasite are mutually "attuned." He termed this "adaptive parasitism." This raised the problem, which had first occurred to him in Ceylon, of how a parasite adapted to species of "one circle of alliance" can pass to those of another. Occasionally it happens that a uredo-form will infect a species where it ordinarily fails. In such a case "its uredospore progeny will thenceforth readily infect that species." Ward regarded this as a case of education. Working on this principle, he succeeded by growing the parasite _successively_ on a series of allied species which were imperfectly resistant, to ultimately educate it to attack a species hitherto immune. He called these "_bridgeing species_." He established, in fact, a complete parallelism between the behaviour of rust-fungi and that of pathogenic organisms in animals.

In the midst of this far-reaching research his health began to fail. In 1904 he had been appointed by the Council to represent the Royal Society at the International Congress of Botany held at Vienna in June of the following year. This he attended, though more seriously ill than he was aware of. On his way back he spent three weeks for treatment at Carlsbad, but receiving no benefit, he went, on the advice of Dr Krause, to Dr von Noorden's Klinik at Sachsenhausen (Frankfort). Nothing could be done for him, and he was advised to return home by easy stages. After a period of progressive and extreme weakness, borne with unflinching courage, the end came somewhat suddenly at Torquay on August 26, 1906. He was buried at Cambridge in St Giles's Cemetery on September 3.

From 1880, the year following his degree, Ward never ceased for a quarter of a century to pour out a continuous stream of original work. This alone would be a remarkable performance, had he done nothing else. But he was constantly engaged in teaching work, and he acted as examiner in the Universities of London and Edinburgh. With no less conscientiousness he complied with the demands which the scientific world makes on its members; he served on the Councils of the Royal (1895) and Linnean (1887) Societies; he was President of the Botanical Section of the British Association at Toronto in 1897, and of the Cambridge Philosophical Society in 1904. Beyond all this he found time to give addresses with unfailing freshness of insight; a lecture at the Royal Institution on April 27, 1894, on the "Action of Light on Bacteria and Fungi" was a notable performance; he wrote numerous articles of a more popular kind, and he produced a number of excellent manuals for students on subjects connected with forest, agricultural and pathological botany. Activity so strenuous almost exceeds the limits of human possibility.

Under the influence of Sachs, Ward might have become a distinguished morphologist. But his work in Ceylon led him into a field of research from which he never deviated. A survey of his performance as a whole, such as I have attempted, has a scientific interest of its own. His research was not haphazard. A continuous and developing thread of thought runs through it all. The fundamental problem was the transference of the nutrition of one organism to the service of another. Of this, in Ceylon, Ward found himself confronted with two extreme types, and of both he made an exhaustive study. In Hemileia it was ruthless parasitism; in Strigula advantageous commensalism. Bornet put Schwendener's theory on a firm foundation when he effected the synthesis of a lichen; Ward, in another group, did the same thing for the ginger-beer plant. In such cases the partnership is beneficial. The problem is to trace the process by which one partner gets the upper hand and becomes merely predatory. Ward inherited a strong taste for music, though I believe he never cultivated it. A musical simile may not inappropriately be applied to his work. In its whole it presents itself to me as a symphony in which the education of protoplasm is a recurring _leit-motiv_.

A few words must be said as to his personal characteristics. He had all the qualifications for the kind of research to which he devoted himself. He was singularly dexterous and skilful in manipulation. He was a refined and accomplished draughtsman, and was therefore able to do himself justice by illustration. He was rigorous in demanding exhaustive proof. This almost deteriorated into a defect. He would pursue every side issue which presented itself in a research, and was quite content if it led to nothing. He would say in such a case: "I will not leave a stone unturned." He was apt, too, I think, to attack a problem in too generalised a form. In his nitrogen work it always seemed to me that he wasted energy on remote possibilities, when a clean-cut line of attack would have served him better[134]. But his mind worked in that way, and he could not help himself. It was, I think, one of the most fertile in suggestion that I ever came across. In later years, in conversation especially, thought seemed to come quicker than words to express it. In this respect he reminded one of Lord Kelvin. In such a predicament he would simply remain silent, and slowly move his head. This habit, I think, explains the reputation of being "mysterious" which he seems to have acquired latterly at Cambridge.

He was not without the honour at home which he deserved, apart from the affection of his friends, and had he lived would doubtless have received it from abroad. He was elected F.R.S. in 1888, and received the Royal Medal in 1893. He was elected an Honorary Fellow of Christ's College in 1897, and received an Honorary D.Sc. from the Victoria University in 1902.

Botanical science could ill spare his loss at the early age of 52. But it may be grateful for 25 years of illuminating achievement. It might have been hoped that another quarter of a century would be allotted to one so gifted. But if the "inexorabile fatum" decreed otherwise, he is at least to be numbered amongst those of whom it may be said

"Felix qui potuit rerum cognoscere causas."

FOOTNOTE:

[134] NOV. 1911. I must guard myself against the implication that Marshall Ward's method was wrong in principle. For as pointed out by Prof. Turner in his "Address to the Mathematical and Physical Section" of the British Association at Portsmouth the maxim of "leaving no stone unturned" is identical with Prof. Chamberlin's "Method of Multiple Working Hypotheses." And what is at first sight an unlikely hypothesis may turn out to be the true one. Yet the rigorous application of the method is time-consuming and life is short. Some liberty of selection in testing the hypothesis that seems most probable must be allowed the investigator, and the instinct of genius may sometimes hit on the right one.

A SKETCH OF THE PROFESSORS OF BOTANY IN EDINBURGH FROM 1670 UNTIL 1887

BY ISAAC BAYLEY BALFOUR

Medicine and Botany--James Sutherland--enforced retirement--the
Prestons--Charles Alston--his career--John Hope--Physiological
leanings--Daniel Rutherford--Robert Graham--John Hutton
Balfour--characteristics--Botanic Society of Edinburgh
founded--appointed to Glasgow--transfer to Edinburgh--his
numerous activities--laboratory teaching established--field
excursions--Ecology--attitude to Darwinism--Alexander Dickson--work
in Organography--his versatility.

My task in the warring against oblivion typified in these addresses is to speak about John Hutton Balfour of Edinburgh, one of the botanical teachers of the middle of last century, whose pupils were numbered by thousands, and whose active life bridged the period of the passing of the old and the birth of the new outlook upon science through Darwin's work; and in relation to what I have to say of him I propose to sketch briefly the stages and development of botanical teaching in Edinburgh from the date when systematised attention was first given to it.

Of the well-recognised fact that the study of Botany as a science has been, to begin with, dependent on Medicine my story furnishes an excellent illustration.

Only towards the end of the seventeenth century had the advance in practice of Medicine in Edinburgh reached a stage which gave urgency to a movement for the improvement in the training of the medical man, and the protection of the public from the attentions of inefficient votaries of the healing art. The foundation of the Royal College of Physicians in 1681 gave expression to the co-operative principle in the control of those who would profess Medicine; the creation of a Botanic Garden for the purpose of the cultivation of medicinal plants was the response in the direction of safeguarding the practitioner against the herbalist, and of giving him the advantage of a correct knowledge of the plants which were the source of the drugs he himself was to compound. Before this time, whilst many practitioners could grow drug-plants for themselves, and did so, the majority were at the mercy of the herbalist.

Two Edinburgh physicians--(Sir) Robert Sibbald and (Sir) Andrew Balfour--conspicuous among their fellows for their activity in promoting the cause of medical education and in the planning of the Royal College of Physicians, were the pioneers of the study of Botany as a science. Determined that the apprentices in Medicine should have adequate opportunity of learning the sources of many of the drugs in use, they acquired a lease of a small area of land in the neighbourhood of Holyrood Palace in which they arranged to cultivate medicinal plants, stocking it from their own gardens and from those of friends. They secured the services of James Sutherland--described as "knowing" in these matters--and placed their small garden under his care, with the obligation that he should instruct the apprentices and lieges in Botany. Sutherland cultivated his plants so well, and the instruction which he gave was so satisfactory, that ere long--no doubt through Sibbald's influence at Court--a portion of the Royal Flower Garden at Holyrood Palace was assigned for the cultivation of medicinal plants, and thither was transferred the collection already made in the hired area. Thus was founded, with the title of Physick Garden, a Royal Botanic Garden in Scotland, and the first Profession of Botany was set up therein by James Sutherland.

Of the earlier years of Sutherland we have no record. His success as a teacher induced the Town Council of Edinburgh--the body in which was vested at the time all the patronage of the University--to institute a Chair of Botany in the University, and to provide for practical teaching in another Botanic Garden belonging to the town. Sutherland was appointed to the Professorship and also to take charge of this new Town Garden, which, it may interest those who at the present day pass through the Waverley Railway Station to know, occupied a portion of the site of that station. Both these gardens were at some distance from the University, and apparently to save the time of the University students, perhaps also to create a teaching garden entirely within the jurisdiction of the College authorities, another portion of ground occupying a part of the Kirk o' Field, notorious as the place of Darnley's murder, was transformed into a herb-garden. Thus within a few years from the beginning of the movement for the providing of adequate facilities to students for learning about plants, three Botanic Gardens were made available.

During Sutherland's tenure of the Professorship teaching was given by him in these different gardens. It would appear, however, that Sutherland was at heart a numismatist, and whilst during the early period of his incumbency of office he had corresponded with many botanical institutions abroad, had introduced to the gardens new species of plants--many of them now established in the flora--and had published in 1683 a _Catalogue of the plants in the Physical Garden_, in later years his interest was centred in coins and medals. So great was the obsession that the patrons of the University, dissatisfied with his botany, compelled him to resign his Chair in 1706, to which they appointed Charles Preston, but Sutherland retained, until he retired in 1715, charge of the Royal Botanic Garden at Holyrood, of which by Royal Warrant he had been made Keeper with the additional personal recognition of Botanist to the King in Scotland. Thus the increase in number of gardens extended to the Professors, and from 1706 onwards to 1739 there were two rival Botanical Schools in Edinburgh--that of the Royal Garden, and that of the University.

Sutherland's place in relation to the development of scientific Botany in Scotland is that of pioneer in the teaching of systematic Botany from the living plants in relation to Materia Medica, and of first custodian and cultivator of plants for instruction in a public garden. His _Catalogue_ is now a book of some rarity--of great rarity in complete state owing to the number of cancel pages--and its reproduction at the present time would have interest alike scientific and historic. It is the first published record of a collection of cultivated plants in Scotland. It tells us the plants which were recognised as indigenous at its date, and from its record we can by correlation with information otherwise obtainable discover the time of introduction to Scotland of alien plants, and thus obtain a basis for gauging their influence on the native Flora as we know it now.

Charles Preston who stepped into the University Chair of Botany vacated in 1706 by Sutherland, was a medical man, an active correspondent of Sloan, Pettiver, and other scientific men in the south. On his death in 1712, after a short tenure of office, George Preston his brother succeeded him and filled the chair until 1739. Both of the Prestons seem to have been chiefly interested in the Materia Medica side of Botany and their teaching was on the lines of it. They are referred to by their contemporaries as men of botanical knowledge and of critical judgment, and their correspondence indicates that they were in touch with the botanical life of their time. Their work in teaching was always in rivalry with that at the Royal Physick Garden. At first no doubt it was effective and useful owing to Sutherland's neglect of his garden, but when a capable active scientific Professor was placed in charge of this Garden the case for such rivalry and duplication of effort ceased, and it is no surprise therefore to find that when a vacancy occurred in 1739 the University Chair was filled by the appointment of the King's Botanist in Charge of the Royal Physick Garden, who was then Dr Charles Alston. And this combination continues to our own time by mutual consent of the Crown and the University.

Sutherland's retirement in 1715 from the Royal Physick Garden four years before his death, which took place in 1719 when he was over 80 years of age, may have been determined by his incapacity for the duties, but it is probable other influences were effective especially as the office of King's Botanist was a Household Appointment and only during pleasure. Were I merely to tell of incidents in the history of Botany in Edinburgh I would here introduce the story of Dr William Arthur, Sutherland's successor at the Royal Garden. Arthur has no botanical claims, but had influential political friends whose zeal on his behalf he ill requited by becoming one of the leaders in the Jacobite plot to capture the Castle of Edinburgh in 1715. Having failed in the attempt he escaped to Italy, where in 1716 he died from a surfeit of figs! Ignoble fate for a King's Botanist!

A man of real distinction now comes into our botanical history in Charles Alston--a clear observer and experimenter.

Charles Alston, born 24th October, 1685, was the third son of Thomas Alston, M.A. of Edinburgh and M.D. of Caen, one of an old Lanarkshire family settled at Thrinacre Milne and connected with the house of Hamilton. After boyhood at Hamilton, Alston went to the University of Glasgow, but before the period for graduation his father died leaving a widow and large family poorly provided for and young Alston's University career was stopped. Through the intervention of the Duchess of Hamilton Alston was then apprenticed in 1703 to a lawyer with a view to his entering the Estates Office of the Hamilton family. But "anatomy and the shops were more agreeable to him than Style Books or the Parliament House" and his "genius inclined more to Medicine," and in 1709 when the Duchess took him into her service as her "Principal Servant," in which position "he had aboundance of spare time," "he ply'd close the Mathematics and whatever else he thought of use to a student of Medicine, particularly Botany." With this training Alston, through the influence of the Hamilton family, was made King's Botanist, Professor of Botany, and Keeper of the Royal Physick Garden in 1716 after the disappearance of Dr Arthur.

He adopted a wise course on succession. Having put the Garden in such order as he could he hied himself to Leyden in 1718 to study under Boerhaave, and returning thence in August 1719 he graduated in Medicine at the University of Glasgow, became Fellow of the Royal College of Physicians, and in June 1720 was able to begin his botanical lectures in the Garden, followed in November by a course on Materia Medica. These courses he carried on until 1739 when he was given the University Chair of Botany and Materia Medica, and the two Botany Schools were thus merged in one. Alston was now colleague of Munro, Rutherford, Sinclair, and other famous men who at this time were increasing the reputation of the University as a Medical School, and he continued to teach Botany and Materia Medica until his death in 1760.

Alston's teaching was mainly directed to the Materia Medica. His full course of lectures on the subject prepared for publication by himself appeared only as a posthumous work edited by his successor Dr Hope, and they reflect the best knowledge of the time, showing rational scepticism of the efficacy of many simples which experiment had not tested. Essays "On Opium," and "On tin as anthelmintic," and an "Index of Simples" published by him tell of his pharmacological investigations, to which his correspondence with Fothergill and others is also witness. The subject in this line to which he gave most attention and on which he wrote three dissertations based on experiments is that of Quicklime and Water--its efficacy in Calculus and also as an agent for keeping water sweet. From Alston, Stephen Hales, then in touch with the Admiralty upon questions of ventilation and other matters of sanitation, obtained early suggestions, and a long correspondence followed.

Alston, who had to earn his livelihood by medical practice, gave much time to the administration of the Botanic Gardens under his charge, and the elaborate lists which he prepared showing the disposition of plants in the Gardens, witness to his interest in their cultivation. His predilection in systematic arrangement was Tournefortian, and on the promulgation by Linnaeus of his "sexual system" in 1736, no writer was more trenchant than Alston in opposition to it, and by this he became widely known. His criticism was directed against it, not as a method of arranging plants by readily recognised characters, but from the standpoint of denial of the existence of sex. By various experiments as well as by argument, Alston endeavoured to disprove the necessity of the stamens for the development of fertile seed, citing cases of seed-production where no application of the "dust" from the stamens was possible--thus early recognising conditions which puzzled botanists for many generations afterwards and until the explanation of apogamy was supplied. One is tempted to wonder whether if the Linnaean system had not received the appellation "sexual" it would have roused the same condemnation from him as it did.

From his published work, notably the _Dissertation on Botany_ (1754) a translation of a portion of his earlier _Tirocinium Botanicum Edinburgense_ (1740), as also from some MS. of his lectures which still exist, we recognise the clearness and vigour of mind of Alston, and the precision of the man is made abundantly evident in the beautiful copper-plate writing in old script of his MS. Page after page is filled without blot or correction, and the whole systematised and arranged without flaw. Anatomical questions were dealt with by him in consonance with the knowledge of the time, mainly resting on Malpighi; but there is no rational treatment of physiological subjects, and this is the more surprising inasmuch as he was in intimate correspondence with Hales, and ought to have been acquainted with the fundamental experimental work of that physiologist. It may be that the fragments of record from which we have to judge are insufficient for correct appraisement, but on all the evidence we possess we must conclude that the two volumes of his _Materia Medica_ give us a picture of the direction of his teaching, and that Botany in the hands of its leading expositor in Edinburgh was at this period only a hand-maid to Medicine.

The advent of Alston's successor, John Hope, was the dawn of new things. The influence of the work of Hales had reached Edinburgh. Comparatively few botanists of to-day have heard the name of John Hope otherwise than as that of a correspondent of Linnaeus and protagonist in this country of his system of classification, for these are the claims to distinction assigned to him by the historians of British Botany; and if one reckons the value of a man's life-work in science by his published writings alone, that of John Hope would be a minimum; for only such papers as those "On Rheum palmatum," "On Ferula Assafoetida," "On Eriocaulon septangulare in Scotland," are extant from his pen. Yet John Hope was a botanist inspired by the spirit of research who obtained by scientific experimental work and explained to his pupils facts of plant physiology some of which the botanical world learned from other workers only a hundred years afterwards. It is difficult to account for Hope's reticence. It may be that he intended to give his work to the world in the book upon Botany which had engaged his attention for many years and of which the MS. was in great part ready at the time of his unexpected death in 1786--if so, the botanical world has been the poorer through the want of Hope's book.

But if Hope did not give cause by published contributions to natural knowledge for his recognition in promoting the advance of Botany, he has always been remembered with gratitude for services of administration which he was peculiarly fitted to render and which profoundly affected the study of Botany in Edinburgh.

John Hope was born 10th May, 1725. The son of Robert Hope, a surgeon in Edinburgh, whose father had become one of the Senators of the College of Justice with the title of Lord Rankeillour. Educated at a famous school in Dalkeith, John Hope, who early showed a liking for Botany, entered the University of Edinburgh as a medical student and became a pupil of Alston. His botanical inclinations tempted him to break the course of his medical studies in Edinburgh to study Botany under Bernard de Jussieu in Paris. Returning to Scotland he graduated in Medicine from the University of Glasgow in 1750, joined the Royal College of Physicians in Edinburgh and began medical practice, giving to Botany such time as could be spared from the many ties of a successful practice. In 1760 Alston died, and John Hope became his successor, first of all in 1761 as King's Botanist at Holyrood and subsequently as Professor of Botany and Materia Medica in the University.

Soon after appointment Hope recognised that to continue to hold "colleges" in Materia Medica meant spoliation of his botanical work. The time had come for a separation of the two subjects of Botany and Materia Medica. Problems of the former now pressing were not those specially relating to medicinal plants. He therefore managed to carry through an arrangement by which he retained a chair as Professor of Medicine and Botany, and a new Professorship of Materia Medica was created. The importance of this step for botanical progress was great--it was not merely a question of time occupied but of scientific outlook.

Another movement in the direction of concentration of effort in the cause of Botany was initiated by Hope early in his official career--that for the creation of a new Botanic Garden in a locality outside the immediate influence of town atmosphere, in which the collections distributed over the Holyrood and Town Gardens could be combined. He accomplished his design, and not only this, but obtained from the Crown a permanent endowment for the new Garden. This was no small achievement--but the omens were favourable, for those patrons of science the Earl of Bute and, later, the Duke of Portland, were in power when the Professor made use of the great influence which his family possessed to secure his ends. A spreading city in time made the location of Hope's new Garden unsuitable, and it was transferred to the present site; but it was the effort by Hope which gave the Botanic Garden, and through it Botany, a status among institutions requiring subsidy and maintenance by Government in Scotland, and the obligation so imposed has been upheld notwithstanding an attempt in later years on the part of the Government to get rid of it--an attempt which the short-sighted policy of the University nearly allowed to succeed.

Hope's duties in his University Chair required of him, in addition to his botanical work, clinical teaching in the Hospital, and he also engaged in practice--this for a livelihood--and took active share in the affairs of the Royal College of Physicians, of which he was President at the time of his death, which occurred in 1786. Botany could therefore claim but a portion of his time.

Having established the new Garden, he laboured with assiduity to lay it out effectively, and then to enrich it with plants. His own ardour and enthusiasm impressed others, and his pupils in all parts of the world contributed to making the Garden a renowned collection of the rarest plants. Here Hope met his students, and here he carried out his many physiological experiments which gave them instruction.

His teaching was comprehensive. Although no longer tied by the calls of his Materia Medica, Hope did not ignore the subject entirely, but plants in this relation were not the groundwork of his instruction. Systematic and descriptive Botany, recognition of herbs, still found a place in it. In Alston the most strenuous opponent of the Linnaean method had gone; it found in Hope a no less strenuous advocate, to whose influence its rapid adoption in this country owed much. To what extent Hope made excursions with his pupils, there is no evidence. His _Hortus Siccus_ and lists of plants with localities show that he was a field-botanist, and in correspondence with, if not more intimately acquainted with, the botanists who were working out the Scottish Flora at the period--such men, for instance, as Lightfoot, Stuart, Robertson. This we do know, that he encouraged his pupils to investigate the Flora of Scotland, giving yearly a gold medal for the best Herbarium, and Hope's "peripatetic pupils" is a designation met with in literature of the time. This aspect of Hope's teaching, consonant with the features of the botanical literature of the period, is that which has been commonly known. It is not however a complete picture. In Hope Scotland had a physiologist of originality and skill--who was not only informed upon the work of Hales, Duhamel, Mariotte and others, but who made his own experiments, clearly devised and effective, and whose catholicity is attested by his dealing with such problems as growth in length and thickness, effect of light and gravity, movement of water, healing of wounds, and the like. This physiology was an essential element of his teaching, and the effect upon students of contact with such direct wresting of truth from Nature must have been immense. Our knowledge of all this, only recently acquired, throws a new light upon Hope's character, and upon the influence which he appears to have exercised on the education of the time. The pity is that he left no published records, and that this bright period of brilliant research should have become obscured by the scholasticism inherent in the method of classification which he himself did so much to popularise.

In accordance with tradition, the Chair vacated by Hope was filled by the election of another medical practitioner in Edinburgh. Daniel Rutherford was born in Edinburgh 3rd November, 1749, the son of Dr John Rutherford, who as Professor was associated with Alston and others in the reformation of the Edinburgh Medical School. He was distinguished both as a classical scholar and as a mathematician, and after graduating M.A. at the University of Edinburgh, he entered on the medical curriculum, obtaining his diploma of M.D. in 1772. His thesis, when applying for the degree, was "De aero fixo dicto aut Mephitico," and by this he became famous through the distinction he established in it between carbonic acid gas and nitrogen, though he did not give nitrogen its name. The exposition he gave of his precise experimental work has been allowed to entitle him to be regarded as the discoverer of nitrogen, although shortly before the appearance of his thesis Priestley had practically, if less methodically, covered the ground. After graduation, Rutherford travelled in France and Italy, returning to Edinburgh in 1775 to begin the practice of Medicine, becoming Fellow of the Royal College of Physicians, of which he was afterwards President.

Rutherford was a chemist, and I have not discovered in any references to him expressions that would show he was at this period of his life interested in plants otherwise than as objects for his experiments in relation to the chemistry of the atmosphere. In seeking for a reason to explain his selection as Hope's successor in the Chair of Medicine and Botany, one may suggest either the general one of recognition of his scientific ability, or the more special one that in experimenting with plants he had been following on the lines of work so conspicuously developed by Hope. And of course at that time some general knowledge of Botany had to be the possession of every successful physician.

Like his predecessors, Rutherford had to undertake clinical teaching in the Hospital; he maintained also his private practice, and was keenly interested in the active literary world of his day in which his nephew (Sir) Walter Scott was a brilliant star. The Botanic Garden continued to hold its place as a scientific institution, and from the advent of William McNab as Principal Gardener in 1810, developed into one of the best known in the world. The recording of the plants of Scotland also proceeded apace; two of the Principal Gardeners of the Edinburgh Garden during Rutherford's Keepership--John Mackay from 1800-1802, and George Don from 1802-1806--being foremost in making known its floristic features, and their work Rutherford must have encouraged. From MS. notes of his lectures, I gather that the biological did not attract Rutherford, nor does it appear in the scanty records available that any special development of teaching equipment or of method took place during his tenure of office.

For some years before his death in 1819 Rutherford had been infirm; and speculation as to his successor had been rife. Robert Brown and Sir James Edward Smith were both spoken of. When the vacancy came Robert Brown refused it and Robert Graham, then Professor in the University of Glasgow, was appointed.

Robert Graham was born at Stirling 3rd December, 1786, the third son of Dr Robert Graham of Stirling (afterwards Moir of Leckie). After early education at Stirling, Graham was apprenticed in 1804 to Mr Andrew Wood, Surgeon in Edinburgh, and entered on the study of Medicine at the University, graduating M.D. in 1808. Thereafter he studied at St Bartholomew's Hospital in London for a year before settling in Glasgow, where he was also Lecturer in Clinical Medicine. During this period he published a dissertation "On continued Fever."

Botany in the University of Glasgow at this time had not reached the dignity of having a Professorship. It was attached to the Chair of Anatomy, but a separate lecturer undertook its teaching. To this lectureship Graham was appointed in succession to Dr Brown. This appointment was the prelude to his election as Professor in 1818 when the Chair of Botany was founded--a foundation which owed much to him through his influence with the Duke of Montrose, then Chancellor of the University, of whose house he was a cadet. One of the first efforts of Graham in his new position was directed to the completion of a scheme that was making for the formation of a Botanic Garden. In this he succeeded, and botanical teaching in Glasgow was thus equipped in 1819.

From this sphere in which he had initiated so much, Graham came to Edinburgh in 1820 as Professor of Medicine and Botany and was forced again to take up medical practice and clinical teaching in the Hospital, and in consequence to interest himself in the affairs of the Royal College of Physicians, of which he became President--all this, as in the case of his predecessors, in addition to his botanical work.

His first labour in relation to Botany was to transfer the Botanic Garden which Hope had made to a new site--that which it now occupies. Nearly two years were required to carry out the removal, to the success of which the skill of William McNab, the Principal Gardener, contributed greatly.

During the whole tenure of his offices Graham devoted himself to the affairs of this Garden, and often in the very practical way of supplying funds from his own resources to supplement the inadequate grants obtained from Government. It gave him the material for the description of many new species which were figured in the _Botanical Magazine_ and other like periodicals. This systematic botanical work was that which Graham cared for most, it was the backbone of his teaching, and all of his scattered papers deal with this aspect of the subject.

In connection with his teaching Graham developed specially the botanical excursion for the study of Field Botany, making it an integral part of his courses, and in furtherance of its aims travelling far through Scotland--a business of a much more arduous nature in days when railways and motors had not annihilated distance and provided all the comforts of civilisation within easy reach of every district. Graham had intended to publish a _Flora_ of Scotland as the result of his practical study of its plants, but it was uncompleted at the time of his death in 1845 after an illness of some duration during which (Sir) Joseph Dalton Hooker acted as _locum tenens_.

Another new method in his teaching was that of encouraging students to write essays upon subjects either practical or theoretical. In this he stimulated investigation. Students in these days had more time than they have now to devote to such things, and of their efforts some were sound pieces of research--the _Botanical Geography_ of Hewitt C. Watson first took form in one of these essays.

John Hutton Balfour[135], who succeeded Graham, was born in Edinburgh 15th September, 1808. The eldest son of Andrew Balfour, surgeon in the Army, who afterwards settled in Edinburgh as printer and publisher, in which business his enterprise was adequate to the venture of the _Edinburgh Encyclopaedia_ under the editorship of (Sir) David Brewster. Andrew Balfour was a grim old presbyterian of the stuff covenanters were made, and in the strict home environment which he created young Balfour early came into touch with theological dogma. The echo of these early impressions remained with him throughout life.

Educated at the High School of Edinburgh where he laid the foundation of sound classical scholarship--always his unobtrusive distinction--Balfour entered the curriculum for the Arts degree at the University. Before completing this he migrated to St Andrews in order to be under the influence of Professor Thomas Chalmers--the famous Divine, afterwards leader in the disruption that founded the Free Church of Scotland--in conformity with the desire of his father that he should become a minister in the Church of Scotland. But Divinity did not claim him and he returned to Edinburgh to begin the study of Medicine--a decision in face of family pressure which is tribute to the strength of purpose which characterised him and found expression frequently in after life.

At the beginning of this renewed Edinburgh curriculum Balfour attended the Botany course of Professor Graham in 1825, and obtained his first scientific instruction in Botany--a subject for which he had always shown fondness. Robert Dickson, afterwards Lecturer on Botany at St George's Hospital, London, was a fellow-student, and together they, in this and following years, made many botanical excursions about Edinburgh. With his fellows Balfour seems to have been _bon camarade_, acquired all the ephemeral distinction attaching to a facile writer of rhymed couplets for occasions, and as an inveterate maker of puns was in demand for the office of punster at the convivial clubs of the period. A mark of more serious attainment--he was President of the Royal Medical Society in two years. After graduation as M.D., when he also became a fellow of the Royal College of Surgeons in Edinburgh--his thesis for the former being "De Strychnia," for the latter "On Purulent Wounds"--Balfour went in 1832 to Paris to continue his medical education, studying there under Dupuytren, Lisfranc, and Manec. Returning, he settled in Edinburgh in 1834 and entered on practice, becoming assistant within and without the University to Sir George Ballingall, Professor of Military Surgery. Amongst his patients he numbered De Quincey and his family. De Quincey's eldest son died from a cerebral complaint, and the autopsy revealed an interesting pathological condition which formed the subject of Balfour's investigation, and an account of it his first published scientific paper.

From the claims of Medicine Balfour could wrest little time for botanical pursuits, but his holiday always meant the botanical exploration of some area, preferably alpine, and his home became a centre for men of kindred tastes. There in co-operation with his old teacher Graham, and with Greville, Forbes, Falconer, Parnell, Munby and others, was instituted in 1836 the Botanical Society of Edinburgh, with wide aims for the promotion of Botany--amongst them the creation of a botanical library and a herbarium. This has proved a signal service to science. It was the pegging out of a claim which has been made effective. The Society after a life--as with all such societies--of fluctuating periods of greater and lesser activity, flourishes still, and its library and herbarium, transferred to the Crown when the space demand of their bulk became urgent, have been the foundation for the large botanical library and herbarium now maintained and subsidised by Government in the Royal Botanic Garden.

Plants gradually drew Balfour away from patients and in 1840 he carried the divorce so far as to establish himself as a teacher of Botany in the Extra-mural Medical School in Edinburgh--that exemplar of free-trade in teaching--from which so many of the famous occupants of Chairs in the University have entered its portals. But only in 1842, when Sir William Hooker moved to Kew and a vacancy was then caused in the Glasgow Chair of Botany to which Balfour was elected, was he able to give up medical practice entirely.

In Glasgow the first years of Balfour's botanical career were spent, but they were few. On the death of Graham he returned to Edinburgh as Professor of Medicine and Botany and Keeper of the Royal Botanic Garden--the electors passing over Joseph Dalton Hooker also a candidate. In the sphere of these offices the rest of his active life was passed until his retirement in 1879. He came to the University of Edinburgh at a time when the reputation of its medical school was upheld by a remarkable band of teachers in the Medical Faculty--Allen Thomson, Alison, Christison, Goodsir, Gregory, Jameson, Simpson, Syme--and when the struggle of the University after a revised constitution was approaching the climax reached in 1858, when with other Scottish Universities Edinburgh obtained autonomy, and science was enfranchised. Of this Faculty he became Dean, and held office until close upon the time when he became Emeritus. In all the discussions and controversies, destructive and constructive, that attached to so weighty a crisis, Balfour's influence and outlook for science were used with effect, and no less influential were his action and advice in subsequent years when the specific question of medical reform was raised, as it so often was.