Chapter VIII: PHYSIOLOGY, MEDICINE, ETC.--Histological Methods.--Section (4)

Dammar is now used as a substitute for Canada balsam. By its use the tissues are rendered more transparent. To prepare it, dissolve one-half ounce of Dammar rosin and one-half ounce of gum mastic in three ounces of benzole, and filter. This may be used to mount unsoftened bone and tooth, hair, brain, and spinal column, and most tissues that have been hardened in alcohol or chromic acid, which require to have their transparency increased.

Glycerine is not adapted for white fibrous tissue or blood vessels, unless they have been hardened in chromic acid, as it causes the white fibers to swell up and lose their normal features. Sections of liver, lung, skin, and alimentary canal show better in glycerine unless they have been stained.

Farrant's solution may be substituted for glycerine in many instances, because of its feebler tendency to render the tissues transparent. It consists of equal parts of gum arabic, glycerine, and a saturated solution of arsenious acid. In mounting preparations with this medium, the covered object should be allowed to lie a day before the varnish is applied, so that the cover may be fixed, and thereby prevented from being displaced. Rectified spirits may be used for mounting softened bone and tooth, and naphtha and creosote are useful for preserving urinary casts.

When the section is mounted in Canada or Dammar balsam, no cement is required, but for all other preservative media the margin of the cover must be covered with cement. To do this, dry the edges of the cover thoroughly with bibulous paper, and paint a layer of gold size, allowing it to overlap the cover an eighth or sixteenth of an inch, then cover this with white zinc cement.

_Preparation for mounting the different tissues_.--To obtain a section of bone or tooth requires a grinding down of the tissue until it is so thin as to be transparent. A section should first be cut as thin as possible by a fine saw. It should be attached by the flattest side to a piece of glass, and then ground down by a grindstone or by very fine emery, on a perfectly flat piece of lead. When sufficiently thin and transparent, mount in rectified spirits or Dammar. Sections of the tongue may be made by embedding in paraffin, and mounted in Farrant's solution or glycerine.

Sections of the stomach may also be made by embedding in paraffin, but better ones can be made by freezing. Farrant's solution makes a good mounting.

The intestines also give a better section from freezing than by embedding, as the paraffin injures the villi; mount in the same medium as the stomach.

The liver may be embedded in paraffin, and the section mounted in Farrant's solution or glycerine. The kidney may be treated in the same way. The cornea of the eye can be readily cut by embedding in paraffin, and the section may be mounted in Farrant's solution. The crystalline lens and retina may be treated similarly.

The brain and spinal cord should be embedded in paraffin or a carrot, and the section mounted in Dammar. Sections of the uterus and ovaries are best mounted in glycerine or Dammar. Sections of lung maybe made by embedding in gum or by freezing, and mounted in Farrant's solution.

Every slide should be of uniform size, and labeled. The usual size is 3×1 inches, and should be of a good quality of glass, free from scratches or air holes. They may be labeled either by writing with a diamond, or a small piece of paper affixed to one end, on which is written what is required.

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LIFE HISTORY OF A NEW SEPTIC ORGANISM.

At a recent meeting in London, of the Royal Miscroscopical Society, Dr. Dallinger gave his annual address to what was probably the largest gathering of Fellows ever assembled on a similar occasion. After briefly referring to the increased interest lately manifested in the study of minute organisms, and recalling the characteristics of the doctrines of abiogenesis and biogenesis, he passed rapidly in review the results of the observations of Tyndall, Huxley, and Pasteur as bearing upon these questions, and called attention to the observations of Buchner as to the transformation of _Bacillus anthracis_ and _Bacillus subtilis_, and _vice versa_, and referred with approval to Dr. Klein's criticisms thereon. Having spoken of the desirability of careful and continuous study of this class of organisms, and the importance of endeavoring to establish the relation of the pathogenic form to the whole group, he said he should be better able to deal with the subject by recording a few ascertained facts rather than by making a more extended review, and he therefore devoted the main part of his address to a description of "the life history of a septic organism hitherto unknown to science." In his observations of this form--extending over four years--he had the advantage of the highest quality of homogeneous lenses obtainable, ranging from one-tenth to one-fiftieth of an inch, his chief reliance being placed upon a very perfect one thirty-fifth of an inch; and from the continuous nature of the observations as well as the circumstances under which they were carried on, dry lenses had for the most part to be employed. Having in his possession a maceration of cod-fish in a fluid obtained from boiled rabbits, he found at the bottom of it, when in an almost exhausted condition, a precipitate forming a slightly viscid mass, to which his attention was particularly directed. It was seen to contain a vast number of _Bacterium termo_, but on examination with a one-tenth inch objective showed that it also contained a comparatively small number of intensely active organisms--one being discovered in about eight or ten drops of the sediment. These measured 1-10,000 of an inch in length by 1-19,500 of an inch in breadth. The fluid had originally been kept at a temperature of 90° to 95° F., and it was noticed that, when placed upon a cold stage under the microscope, the movements of the organisms became, gradually slower, until at last they entirely ceased; the necessity, therefore, arose for the use of a warm stage, and the very ingenious contrivance by which a continuous and even temperature was maintained within the one-tenth of a degree was exhibited. The greatest difficulty in the matter was, however, experienced in obtaining specimens for observation, in order to be able to trace them from their earliest to their latest stage. The President then explained, by means of an admirable series of illustrations projected upon a screen by the oxyhydrogen lantern, the life history of the organism to which he had referred, exhibiting it first as a translucent, elliptic, spindle-shaped body, with six long and delicate flagella, the various positions in which the five specimens were drawn giving a very good idea of its peculiar porpoiselike movements.

The various positions which it assumed in making an attack upon a portion of decomposed matter were also shown, the movements quite fascinating the observer by their rhythmical character. The supposed action of the flagella in the production of the movements observed was explained, distinct evidence being afforded of a remarkable spiral motion, at least of those behind. The process of fission was illustrated in all its observed stages from the first appearance of a construction to that of final and complete separation, the whole being performed within the space of eight or nine minutes. A description of the process of fusion from the simple contact of two organisms to their entire absorption into each other followed, as well as their transformation into a granular mass, which gradually decreased in size in consequence of the dropping of a train of granules in it wake as it moved across the field. The development of these granules was traced from their minute semi-opaque and spherical form to that of the perfect flagellate organism first shown, the entire process being completed in about an hour. Experiments as to their thermal death-point showed that, while the adults could not be killed by a temperature less than 146° F., the highest point endured by the germs was 190° F. Illustrations of a variety of other modes of fission discovered in previous researches on similar forms were given, showing the mode of multiple division and a similar process in the case of an organism contained in an investing envelope. The President concluded his address, which was listened to throughout with the greatest attention, by remarking that, though the processes could be seen and their progress traced, the _modus operandi_ was not traceable. Yet the observer could not fail to be impressed with the perfect concurrent adaptation of these organisms to the circumstances of their being; they were subject to no caprices, their life-cycles were as perfect as those of a crustacean or a bird, and while the action of the various processes was certain, their rapidity of increase and the shortness of their life history were such that they afforded a splendid opportunity of testing the correctness of the Darwinian law.

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WINTER AND THE INSECTS.

For a number of years previous to 1878 we had in Pembroke but little or no severe cold, owing to the prevalence of southeast, south, west, and especially southwest winds. In many places, fuchsias that were left in the ground for the entire year had not been frozen to the root within the memory of man. Some of these plants had grown to be trees five or six yards in height, and with a trunk the size of one's leg. Now, during the same series of years, many insects that are common throughout the rest of Great Britain did not cease to be rare with us, or rather were confined to certain circumscribed limits. Thus, the Noctuellae, with the exception of a few species abundant everywhere, were almost wanting, and I know of no other country where the dearth of common species of nocturnal butterflies was so great. But during the winter of 1878 there supervened a radical change. Persistent winds from the northwest, driving back the currents of warm air from the south, brought on an intense cold that froze everything; or, when some variation occurred in them, clouds formed and dissolved into a rain that immediately froze, so that the large roads remained for weeks covered with a layer of rime from two to four inches thick.

The winters of 1879 and 1880 were equally cold; we may even say that the latter was the severest that had been experienced in fifty years. This year the sea-sand, along with the ice and snow, formed a thick crust all along the tide-line--this being something rarely seen along our coast. The first of these three winters (1878-1879) killed all the arborescent veronicas and a few sumacs. As for the fuchsias and myrtles, they were frozen down to the level of the soil.

I now come to the effects of this severe cold upon the insects.

The Lepidoptera, which before were rare, became more and more common in 1879, 1880, and 1881, and so much so that during the last named year they abounded; and species that had formerly been detected only at certain favored points spread over the entire coast and into the interior of the country. The geometers appeared in numbers that were unheard of. But this change was especially striking as regards the Noctuellae, in view of the previous rarity of the individuals belonging to this family.

We have here an example of the direct relation of cause to effect, although I am not in a position to assert that the effect is always produced in the same way. To me there is no question as to the fact that the constitution of those insects which nature has accorded the faculty of liberating is strengthened, and that their chances of life are increased, if the cold of winter is intense enough to plunge them into an absolute rest, and is not unseasonably affected by warm, spring-like days. It is certain that such cold is capable of contributing largely to the multiplication of the individuals of such species as hibernate in the egg state, and it also has a beneficent influence upon those species which, like the small social larvae, pass this season upon the earth enveloped in a silken envelope, or, like the larvae of the Noctuellae, between dead leaves or upon the ground itself.

On another hand, it cannot be doubted that mild winters greatly contribute to the bringing about of a destruction of larvae and chrysalids in two ways: First, they favor the development of mould, which, as well known, attacks the larvae of insects when these have been enfeebled by an excess of rain or dampness; and second, they permit beasts of prey to continue to exercise their activity. Now, these latter are numerous. Moles, instead of burying themselves deeply, then continue to excavate near the surface, and shrew mice are constantly in search of food. These small mammals, which abound in this district, destroy a large number of chrysalids of Lepidoptera.

It is the same with birds. As soon as severe cold begins to prevail in the north and east, they come in troops to the open fields and the sheltered slope of the hills of our district. But it is scarcely worth while to stop to tell of the skill and perseverance of these destroyer of larvae. We may mention, the woodpecker, however, as a skillful searcher for insects that lie hidden in places where the sun has melted the snow. The carnivorous Coleoptera and the Forficulae are likewise generally in motion during mild winters. Doubtless these last-named do not make very large inroads in the ranks of larvae and chrysalids every day; yet, having no other food, they destroy a goodly number of them. But I believe that the devastations made in the army of insects by all these enemies united do not equal those made by certain crustaceans--the wood lice.

During mild winters these pests multiply, eat, and prosper out of bounds, and to such a point that, in a climate like ours, they become a true scourge that prevails everywhere, out of doors and within. Once in a place, they begin to look for larvae and chrysalids, which they devour. The severe cold seems to have destroyed a certain number of them, since they are now not so numerous by far; and it has at least certainly put a stop to their devastations at an epoch when the larvae are more particularly exposed to the attacks of their enemies. It is to this cause, as well as to the preceding, that I am led to attribute the extraordinary multiplication of so many species during the three last summers, which were separated by severe winters. Last winter was mild, and there is therefore no reason to expect that there will be another multiplication; but I hope that the harm done by such a season will be slight. It is the progressive multiplication of the destroyers, joined to the correlative disappearance of the victims caused by a series of temperate seasons, that is to be feared.

In support of the proposition that I maintain, I may mention still another fact. While this district (Pembroke, Wales) is relatively poor in species whose larvae feed and hibernate in the open air a few species of Noctuellae, whose larvae live buried in the earth, are always abundant. The country is relatively rich in spices of _Tortrix_, which develop and hibernate in the stalks or roots of plants. It is also worthy of remark that very few of our species seem to be incapable of enduring a severe winter.--_C.G. Barret, in Science et Nature_.

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SILK WORM EGGS.

Prof. C.V. Riley, entomologist, announces that the Department of Agriculture, Washington, will purchase during the coming summer such quantities of silk worm eggs as may be deemed necessary for the distribution that it is proposed to make for the season of 1886. So far as found practicable, the eggs will be purchased of American producers. There are certain precautions, however, that must be taken to insure purchase. Eggs of improved races only (preferably of the French or Italian Yellow Races) will be bought, and the producer should send one or two samples of pierced cocoons with the eggs. In addition to this the producer must conform to certain rules to be hereafter explained, so that an examination may be made that will serve to show the degree of purity of the eggs. No silk culturist should use his crop for the production of eggs unless the worms have shown, until they began the spinning of their cocoons, every sign of perfect, robust health. Any indication of the disease called _flacherie_, from which the worms so often die after the fourth moult and turn black from putrefaction, or of any other disease from which silk worms suffer, should be considered as ample reason for not using the cocoons for the purpose in question. They should, on the other hand, be sold for the filature. If the worms have all the indications of health until the spinning period, then the cocoons may be used for the production of eggs. The following brief instructions will prove of service to those who which to secure sound eggs:

For each ounce of eggs to be produced, about three-quarters of a pound of fresh cocoons from the finest and firmest in the lot should be chosen. These should be strung in sets upon a thread, care being taken not to pierce the chrysalis, and the strings hung in a cool, darkened room. The moths generally emerge from the cocoons early in the morning, and will be seen crawling about over these, the males being noticeable by their smaller abdomens, more robust antennae, and by their greater activity. The moths should be placed, regardless of sex, on a table, where they will soon find their mates and couple. As soon as formed, the couples should be removed to another table, that they may not be disturbed by the flutterings of the single moths.

There should be prepared for each ounce of eggs to be produced, about one hundred small bags of fine muslin, made in the following manner: Cut the cloth in pieces 3×6 inches. Then fold one end over so as to leave a single edge of about three-quarters of an inch, as shown in the accompanying cut. This should be sewn up into a bag with the upper end open, and then turned inside out, so that the seams will cause the sides to bulge. Thus completed they are called "cells." The cells should be strung on a cord stretched across the room.

The moths couple as a rule about eight o'clock in the morning. About four in the afternoon they should be separated by taking them by the wings and drawing them gently apart. Each female should now be placed by herself in a cell, which is then closed by a pin as shown in the figure. Here she will lay her eggs and in due time die. The males may as a rule be thrown away, but it is wise to keep a few of the more active ones, in case there should be a superabundance of females the following day.

When the females have finished laying their eggs, which operation occupies about thirty-six hours, they are ready to be shipped to this office. The cells, with their inclosed moths and eggs, should be placed in a strong box of wood or tin, being packed in such a manner that they will not be crushed, and mailed to the entomologist at the department. By using the inclosed return penalty slip, payment of postage may be avoided. The name of the sender should be placed in each box. The moths, as soon as received, will be examined microscopically, and the eggs of those which are found to be free from disease will be weighed and paid for at the rate of $2.50 per ounce of 25 grammes (about 6-7 of an ounce avoirdupois). Silk culturists are advised not to attempt the production of eggs unless they are adepts at the industry, and have had at least one season's experience. We would advise each person desiring to sell, to send a sample first, with a statement of the quantity offered.

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Dr. Zintgraff of Bonn has taken a phonograph with him to Africa. He intends to bring home phonograms of the savage dialects which he will hire the natives to speak into the machine.

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[NATURE.]

DETERMINING THE MEAN DENSITY OF THE EARTH.

In _Nature_ for March 5 (p. 408) Prof. Mayer suggests an improvement in our method of determining the mean density of the earth, from which it appears that our plan has not been properly understood. This misunderstanding, no doubt, has arisen from the incomplete description of our method given in the _Nature_ (Jan. 15. p. 260) report of the _Proceedings_ of the Berlin Physical Society, which report was probably the only source of information accessible to Prof. Mayer. We are led therefore to give a short description of our method.

Let H I K L represent a section of a cubical block of lead, about two meters in the edge, and weighing 100,000 kilos. The balance, A B C, is placed in the middle of the upper horizontal surface. It bears the scale-pans, D and E. Under these scale-pans the block is bored vertically through, and two other scale-pans, F and G, are suspended below the block, attached to the balance by means of rods passing through these openings.

A weight D is brought into equilibrium by weights in G. The weight in D is acted upon by the earth's attraction + that of the block, and that in G by the earth's attraction - that of the block. The weights in G are then greater than that in D by twice the attraction of the block. The weight in D in now removed to F, and counterbalanced by weights in E. The weight in E will be less than that in F by twice the attraction of the block. The difference of the two weighings gives therefore four times the attraction of the block. A correction must be introduced for the variation in the earth's attraction due to the different heights of D, E and F, G.

In order to obtain as great a deflection of the balance by the method suggested by Prof. Mayer, each of the mercury spheres must exert the same attraction as our lead block. This would require spheres having radii of about one meter. The length of the beam of the balance would be necessarily at least two meters. Besides, each mass of mercury, would exert some attraction on the weight on the other side, and thus lessen the deviation of the balance.

The method given by Prof. Mayer, except for the suggested employment of mercury, is then no improvement on ours. If we should use mercury, we would construct a cubical vessel to contain it, and use it as we propose to use the lead block. The advantage of using mercury is, however, counterbalanced by the difficulty of obtaining it in such large quantities as would be necessary.

ARTHUR KONIG.

FRANZ RICHARZ.

Berlin, Physical Institute of the University, March 15.

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PHYSICS WITHOUT APPARATUS.

_The Porosity and Permeability of Bodies._--Take two tumblers of the same size, place one of them upon a table, and pour into it a small quantity of nearly boiling water. Cover this glass with a sheet of cardboard, and invert the other one upon it. This second tumbler must be previously wiped so as to have it perfectly dry and transparent. In a few seconds the steam from the lower tumbler will traverse the cardboard (which will thus exhibit its permeability), and will gradually fill the upper tumbler, and condense and run down its sides. Wood and cloth may be experimented with in succession, and will give the same results; but there are other substances that are _impermeable_, and will not allow themselves to be traversed. Such, for example, is the vulcanized rubber of which waterproofs are made. This experiment explains to us why fog is, as has been well said, so _penetrating_. It traverses the tissue of our overcoat and of our flannel, and comes into contact with our body. On the contrary, a rubber coat preserves us against its action.

_A Hot Air Balloon_.--Make a hollow cylinder of small diameter out of a sheet of paper such as is used for cigarette packages, and turn in the ends slightly so that it shall preserve its form. If the cylinder seems too difficult to make, a cone may be substituted. Now set fire to the cylinder or cone at its upper part. The paper will burn and become converted into a thin sheet of ashes, which will contract and curl inward. This light residuum of ashes, being filled with air rarefied by combustion, will suddenly rise to a distance of two or three yards. Here we have a Montgolfier balloon.--_La Nature_.

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THE CASINO AT MONTE CARLO.

The little city is situated about half way between Nizza and Mentone, and it formerly was the chief city of a principality that belonged to the family Grimaldi. Prince Florestan sold in 1860 his royal prerogatives to the Emperor Napoleon, for three million francs, consequently the land came under the jurisdiction of the French republic, but the city remained in the Prince's possession, who, however, gave to the gambler Blanc the privilege of erecting a gambling house upon the rocky shore of the sea.

Enormous sums of money were spent to give this isolated cliff its present appearance, covered as it is with beautiful buildings, hotels, and villas, besides the magnificent Casino building, which was erected in 1862. Directly facing the sea, there is a succession of most beautiful gardens and terraces.

But this establishment, which seems like paradise, has had a most disastrous effect upon thousands of persons, and for a long time the subject of influencing the French government to put a stop to this gambling house has been agitated. It can scarcely be imagined how much misery it has already caused. It is evident to every one that the keeper of the bank makes considerable profit, as the chances are 63 times greater in his favor than those of the player.

It is admitted that the profits amount every year to 17 million francs. One can well imagine how many fortunes have been consumed every year to make this profit; but the number cannot be determined.

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ON AN EXPRESS ENGINE.

It is a somewhat unpromising morning--the river is dark with fog and the huge arch of the station nearly hidden by mist and steam. A cold, damp wind makes the passengers hurry into the carriages, and strikes us sharply as we step on to the foot-plate of the engine, which has just joined the train. But as we get behind the shelter of the screen, we feel a generous and slightly unctuous sensation of warmth very comforting to a chilly man. The brasswork of the engine shines brilliantly, the footboard has been newly scrubbed, and the driver and stoker stand waiting for the signal. The needle shows that the steam is just below the pressure at which it would begin to blow off; the water in the gauge glass is just where it ought to be; in fact, the engine is in perfect condition and ready for a start. The line is clear, the guard's whistle is answered by our own, and we glide almost imperceptibly past the last few yards of the platform. The driver opens the regulator till he is answered by a few sounding puffs from the funnel, and then stands on the lookout for signals so numerous that one wonders how he can tell which of the many waving arms is raised or lowered for his guidance.

So he goes on, with hand on regulator and lever, gradually admitting more steam as signal after signal comes nearer and then flies past us, till at last we are clear of the suburbs and find ourselves on a gentle incline and a straight road, with the open fields on either side. It is now that the real business of the journey begins. Locomotives are as sensitive and have as many peculiarities as horses, and have to be as carefully studied if you would ride them fast and far. The lever is put into the most suitable notch for working the steam expansively; the driver's hand is on the regulator, not to be removed for the rest of the trip; the furnace door is thrown wide open, and firing begins in earnest. Here it may not be amiss to state, for the benefit of the uninitiated, that the regulator controls the supply of steam from the boiler, while the lever enables the driver to reverse the engine, or, as we have already stated, to expand the steam by cutting it off before the end of the stroke. The engine answers to the appeal like a living thing, and seems, with its steady beat and sonorous blast, to settle down to its work. It is pleasant from our seat in the corner of the screen to see this preparation for the work ahead--the absolute calm of driver and stoker, who exchange no word, but go steadfastly and quietly about their business; to feel the vibrations from the rails beneath throb through one with slowly increasing rapidity, or watch the trees and houses go past as gulls flap past a boat. For there is a certain apparent swagging movement of the objects past which one travels which can only be likened to the peculiar flight of a large sea-bird. But now there are signs of increased activity on the foot-plate; the stoker is busy controlling the feed of water to the boiler, and fires at more frequent intervals; the driver's hand moves oftener as he coaxes and encourages the engine along the road, his slightest gesture betraying the utmost tension of eye and ear; the stations, instead of echoing a long sullen roar as we go through them, flash past us with a sudden rattle, and the engine surges down the line, the train following with hot haste in its wake. We are in a cutting, and the noise is deafening. Looking ahead, we see an apparently impenetrable wall before us. Suddenly the whistle is opened, and we are in one of the longest tunnels in England. The effect produced is the opposite of that with which we are familiar in a railway carriage, for the change is one from darkness to light rather than from light to darkness. The front of the fire-box, foot-plate, and the tender, which had been rather hazily perceived in the whirl of surrounding objects, now strike sharply on the eye, lit up by the blaze from the fire, while overhead we see a glorious canopy of ruddy-glowing steam. The speed is great, and the flames in the fire-box boil up and form eddies like water at the doors of an opening lock. Far ahead we see a white speck, which increases in size till the fierce light from the fire pales, and we are once more in open day. The weather has lifted, the sky is gray, but there is no longer any appearance of mist. The hills on the horizon stand out sharply, and seem to keep pace with us as the miles slip past. The line is clear; but there is an important junction not far distant, and we slacken speed, to insure a prompt pull-up should we find an adverse signal. The junction signals are soon sighted; neither caution nor danger is indicated, and, once clear of the station, we steam ahead as fast as ever. One peculiarity of the view of the line ahead strikes us. Looking at a railroad line from a field or neighboring highway, even where the rails are laid on a steep incline, the rise and fall of the road is not very strikingly apparent. Seen through the weather-glass, the track appears to be laid up hill and down dale, like a path on the downs above high cliffs. Over it all we advance, the engine laboring and puffing on one or two heavy gradients, in spite of a full supply of steam, or tearing down the inclines with hardly any, or none at all and the brake on. And here it may be noted that, like modern men, modern engines have been put upon diet, and are not allowed to indulge in so much victual as their forefathers. The engine-driver, like the doctor of the new school, is determined not to ruin his patient by over-indulgence, and will tell you severely enough that "he will never be guilty of choking his engine with an over-supply of steam." In the mean time, the character of the country we travel through has changed. It has become more open, and there is a stiff sea-breeze, which makes itself distinctly felt through the rush of air produced by the speed at which we are going. We fly past idle streams and ponds, and as the steam swirls over them are disappointed at producing so little effect; but the ducks, their inhabitants, are well used to such visitations, and hardly deign to move a feather. Suddenly we plunge into a series of small chalk cuttings, and on emerging from them find ourselves parallel with a grand line of downs. We speed by a curve or two, and find ourselves on the sea-shore; one more tunnel, and with steam off we go soberly into the last station. But there is one step more. The breeze blows about our ears. Before us the rails are wet, for the sea swept over them not many hours since, and to accomplish the last few yards of our journey the lever controlling the sand-box must be used liberally, to prevent slipping; the signal is given, and at a walking pace we make our way to where the steamer is awaiting us. A gentle application of the brake pulls us up, and the journey is over. It is difficult to realize, as the engine stands quietly under the lee of the pier while the driver examines the machinery, and the fire, burned low, throws out a gentle warmth as we stand before it, that half an hour ago we were tearing along the line at full speed, while the foot-plate that is now so pleasant to lounge on throbbed beneath us. Nothing now remains but to kill time as best we may till the return trip many hours hence. It scarcely promises to be as comfortable as our morning ride, for the weather has changed--it is blowing half a gale, and the rain comes down in sheets. Our train is timed to start in the small hours, and the night seems dirty and depressing enough as we make our way for a cup of coffee to the refreshment room, where a melancholy Italian sits in sad state eating Bath buns and drinking brandy. We walk past the train, laden with miserable sea-sick humanity, and step on the engine, which stands in the dark at the end of the platform. Time is up, and we pass from the dim half-light of the station into outer darkness. A blacker night there could hardly be; looking ahead there is nothing to be seen but one's own reflection in the weather-glass. We are in the midst of obscurity, which suddenly changes to a rich light as the whistle is opened and we enter a tunnel. The effect is far more striking than in the daytime. The light is more concentrated, and the mouth of the tunnel we have just entered might be the entrance to Hades--for there is no telltale spot of light to prove to our senses the existence of any opening at the other end. The sound echoed from the walls and roof has a tremendous quality, and resolves itself into a grand sort of Wagnerian rhythm, making a vast crescendo, till with a rush we clear the tunnel, and are once more under the open sky. The pace is increasing, the steady beat of the engine tells more distinctly on the ear than in the daytime; the foot-plate is lit up by the glare from the fire-door; but still there is nothing to be seen ahead but the impenetrable night. Looking back, however, the scene is very different. The tender and guard's van glow in the light thrown by the fire, trees and houses by the side of the track stand out sharply for a moment and are then lost to sight, the light from the carriage windows produces the effect of the wake of a ship seen from the stern. Gradually the clouds have rolled away, leaving the sky clear. The moon is seen fitfully through the whirling steam; the surrounding country is visible for miles round. The effect produced is unspeakably beautiful. In the mean time let us turn our attention to the working of the engine. In the first place, let us take note that, although the engine we are now on, and that which took us from London, belong to the same type, their performances are somewhat different. No two engines ever resemble each other, no matter how carefully they may have been built from the same plan, neither do any two drivers manage their engines precisely in the same way. We have in this instance an excellent opportunity of comparing two different methods of driving. It is the driver's principal object to get the required amount of work out of his engine with the smallest possible expenditure of coal and water. To obtain this result the steam must be worked expansively, which is done by placing the valve gear in such a position by means of the lever that the supply of steam to the cylinders is cut off, as we have stated at the beginning of this article, before the piston has accomplished its full stroke. There are two ways of controlling the speed of an engine worked, as all locomotives are worked now, expansively. You may keep the regulator wide open, so that there is always a full supply of steam on its way to the cylinders, in which case you increase or diminish the speed by using the steam more or less expansively through the agency of the lever. Or you may work with the same amount of expansion throughout the journey, and have command of the engine by constantly changing the position of the regulator. There is no doubt that the men who employ the latter method save something by it, although this would hardly seem to be the opinion of the driver who is bringing us rapidly nearer to London, for unlike the driver whom we accompanied on the daylight journey, his hand is not often on the regulator. As we rush on past countless signals, punctual to the minute, yet always having ample time to slacken speed before we come to the places where the different colored lights cluster thickest, we are reminded once more how much is required of an express engine-man besides a thorough acquaintance with the machinery he has to control. Traveling at night at a great speed, he must know every inch of the road by heart--where an incline begins and where it ends, and the exact spot at which every signal along the line may be first sighted. He must have completely mastered the working of the traffic on both the up and down lines, and, above all, must be ready to act with the utmost promptitude should anything go wrong. Mr. Michael Reynolds' publications have done much toward enlightening the public on these points, but we doubt if there are many who really know the amount of toil and danger cheerfully faced by the men on the engine, who hold their lives in their hands day after day for many years. These thoughts occur to us as we recross the Thames and pull up at the platform after a thoroughly enjoyable run.--_Saturday Review_.

* * * * *

The mucilage on postage stamps may not be unhealthy, but persons having a good many to affix to letter envelopes, circulars, newspapers, or other wrappers every day, will consume considerable gum during a year. A less objectionable mode of affixing stamps than the one usually employed is to wet the upper right hand corner of the envelope, and press the stamp upon it. It will be found to adhere quite as well as if the stamp went through the moistening process.

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ERYTHROXYLON.

[Footnote: From an "Ephemeris of Materia Medica, Pharmacy, Therapeutics, and Collateral Information." By Edward E. Squibb, M.D., Edward H. Squibb, S.B., M.D., and Charles F. Squibb, A.B.]

COCA.

The condition of the principal markets of the world for this drug has recently been exceptionally bad. That is, whether good coca was sought for in the ports of Central and South America, or in London, Hamburg, or New York, the search, even without limitation in price, was almost invariably unsuccessful. Not that the drug, independent of quality, was scarce, for hundreds of bales were accessible at all times; but the quality was so poor as to be quite unfit for use. The samples, instead of being green and fragrant, were brown and odorless, or musty and disagreeable, at once condemning the lots they represented, to the most casual observation, and yet the price was high enough to have represented a good article. The best that could be done by the most careful buyers was to accept occasional parcels, the best of which were of very inferior quality, and therefore unfit for medicinal uses, and these at very high prices. Coca is well known to be a very sensitive and perishable drug, only fit for its somewhat equivocal uses when fresh and green, and well cared for in packing and transportation. Very much like tea in this and other respects, it should be packed and transported with the same care and pains, in leaded chests, or in some equivalent package. It is very well known that tea, if managed, transported, handled, and sold as coca is, would be nearly or quite worthless, and therefore coca managed as the great mass of it is must be nearly all of it comparatively worthless. If used as tea is, this would probably soon appear; but when used as a medicine which has been highly extolled and well advertised, it seems to go on equally well whether of good or bad quality. It is pretty safe to say that nineteen-twentieths of the coca seen in this market within the past two years must be almost inert and valueless, yet all is sold and used, and its reputation as a therapeutic agent is pretty well kept up. At least many thousands of pounds of the brown ill-smelling leaf, and of preparations made from it, are annually sold. And worse than this, considerable quantities of a handsome looking green leaf, well put up and well taken care of, have been sold and used as coca, when wanting in nearly all its characteristics.

The writer for more than a year past has seen but one or two small lots of moderately good coca, and in common with other buyers has been obliged to buy the best that could be found to keep up his supply of the fluid extract. Almost every purchase has been made on mental protest, and he has been ashamed of every pound of fluid extract sent out, from the knowledge that it was of poor quality; and there seems to be no more prospect of a supply of better quality than there was this time last year, because so long as an inferior quality sells in such enormous quantities at good prices the demands of trade are satisfied.

Under this condition of the markets, the writer has finally decided to give up making a fluid extract of coca, and has left it off his list, adopting a fluid extract of tea instead, as a superior substitute, for those who may choose to use it, and regrets that this course was not taken a year ago.

The character of coca as a therapeutic agent is not very good. The florid stories of a multitude of travelers and writers, up to and including the testimony of Dr. Mantegazza, received a considerable support from so good an authority as Sir Robert Christison, who reported very definite results from trials made upon himself, and upon several students under his immediate control and observation; and his results seem to have led to a very careful and exhaustive series of observations at University College, London, by Mr. Dowdeswell. This paper, published in _The Lancet_ of April 29 and May 6, 1876, pp. 631 and 664, is entitled "The Coca Leaf: Observations on the Properties and Action of the Leaf of the Coca Plant (Erythroxylon coca), made in the Physiological Laboratory of University College, by G.F. Dowdeswell, B.A." The results of these investigations were absolutely negative, and at the close of the work the investigator says: "Without asserting that it is positively inert, it is concluded from these experiments that its action is so slight as to preclude the idea of its having any value either therapeutically or popularly; and it is the belief of the writer, from observation upon the effect on the pulse, etc., of tea, milk and water, and even plain water, hot, tepid, and cold, that such things may, at slightly different temperatures, produce a more decided effect than even large doses of coca, if taken at about the temperature of the body."

Conflicting and contradictory testimony from competent authority is not uncommon in therapeutics, and the reasons for it are well recognized in the impossibility of an equality in the conditions and circumstances of the investigations, and hence the general decision commonly reached is upon the principle of averages.

There can hardly be a reasonable doubt that coca, in common with tea and coffee and other similar articles, has a refreshing, recuperative, and sustaining effect upon human beings, and when well cultivated, well cured, and well preserved, so as to reach its uses of good quality and in good condition, it is at least equal to good tea, and available for important therapeutic uses. Mr. Dowdeswell supposed that he used good coca, but it is very easy to see that with any amount of care and pains he may have been mistaken in this. Had he but used the same parcel of coca that Sir Robert Christison did, the results of the two observers would be absolutely incomprehensible; and the results, in the absence of any testimony on that point, simply prove that the two observers were using a different article, though under the same name, and possibly with the same care in selection. On Sir Robert Christison's side of the question there are many competent observers whose testimony is spread over many years; while on Mr. Dowdeswell's side there are fewer observers. But there has been no observer on either side whose researches have been anything like so thorough, so extended, or so accurate as those of Mr. Dowdeswell. Indeed, no other account has been met with wherein the modern methods of precision have been applied to the question at all; the other testimony being all rather loose and indefinite, often at second or third hands, or from the narratives of more or less enthusiastic travelers. But if Mr. Dowdeswell's results be accepted as being conclusive, the annual consumption of 40,000,000 pounds of coca at a cost of 10,000,000 dollars promotes this substance to take rank among the large economic blunders of the age.[9]

[Footnote 9: An excellent summing up of the character and history of coca, from which some of the writer's information has been obtained, will be found in "Medicinal Plants," by Bentley and Trimen, vol. i., article 40.]

The testimony in regard to the effects of tea, coffee, Paraguay tea, Guarana and Kola nuts, is all of a similar character to that upon coca. Each of these substances seems to have come into use independently, in widely separated countries, to produce the same effects, namely, to refresh, renew, or sustain the physical and mental organism, and it was a curious surprise to find, after they had all been thus long used, that although each came from a different natural order of plants, the same active principle--namely, caffeine--could be extracted in different proportions from all. It is now still more curious, however, to find that for centuries another plant, namely coca, yielding a different principle, has been in use for similar purposes, the effects of which differ as little from those of tea, coffee, etc., as these do among themselves. Yet cocaine is chemically very different from caffeine, simply producing a similar physiological effect in much smaller doses. All these substances in their natural condition seem to be identical in their general physiological effect, but idiosyncrasy, or different individual impressibility or sensitiveness, causes a different action, as well in quality as in degree from the different substances, upon some persons.

In order to throw a little additional light on the comparative activity of the principal individuals of this group of substances, the following trials were made. It is generally admitted, and is probably true, that the same power in these agents which refreshes, recuperates, and sustains in the condition which needs or requires such effects also counteracts the tendency to sleep, or produces wakefulness when a tendency to sleep exists; and, therefore, if a tendency or disposition to sleep could be prevented by these agents, this tendency might be used as a measure of their effects when used in varying quantities, and thus measure the agents against each other for dose or quantitative effect. In this way the proposition is to first measure coca against tea, then coffee against guarana, and finally to compare the four agents, using pure caffeine as a kind of standard to measure by.

An opportunity for such trials occurred in a healthy individual sixty-five years old, not habituated to the use of either tea, coffee, tobacco, or any other narcotic substances, of good physical condition and regular habits, and not very susceptible or sensitive to the action of nervines or so-called anti-spasmodics. Quantities of preparations of valerian, asafoetida, compound spirit of ether, etc., which would yield a prompt effect upon many individuals seem to have little or no effect upon him, nor do moderate quantities of wines or spirits stimulate him. That is to say, he has not a very impressible nervous organization, is not imaginative, nor very liable to accept results on insufficient or partial evidence.

Fully occupied with work, both physical and mental in due proportion, for more than ten hours every secular day, when evening comes he finds himself unable to read long on account of a drowsiness supposed to be of a purely physiological character. With a full breakfast at about 7:30, a full dinner at about 2:30, and a light evening meal about 7, and no stimulants, or tea, or coffee at any time, he finds, as a matter of not invariable but general habit, that by half past 8 drowsiness becomes so dominant that it becomes almost impossible, and generally impracticable, to avoid falling asleep in his chair while attempting to read, even though ordinary conversation be carried on around him.

The first trial to combat or prevent this drowsiness was made with caffeine. The first specimen used was a very beautiful article made by Merck of Darmstadt, and after that by pure specimens made for the purpose, the two kinds being found identical in effect.

Commencing with a one grain dose at about 6:30 P.M., on alternate evenings, leaving the intermediate evenings in order to be sure that the nightly tendency still persisted, and increasing by half a grain each alternate evening, no very definite effect was perceived, until the dose reached 2½ grains, and this dose simply rendered the tendency to sleep resistible by effort. After an interval of three evenings, with the tendency to sleep recurring with somewhat varying force each evening, a dose of 3 grains was taken, the maximum single dose of the German Pharmacopoeia. This gave a comfortable evening of restedness, without sleep or any very strong tendency to it until ten o'clock. Without anything to counteract sleep, the rule was to read with difficulty by nine, without much comprehension by quarter past nine, and either be asleep or go to bed by half past nine. The 3 grain dose of caffeine repeatedly obviated all this discomfort up to ten o'clock, but did not prevent the habitual, prompt, and sound sleep, from the time of going to bed till morning.

This was the model established, upon and by which to measure all the other agents, and they were never taken nearer than on alternate evenings, with occasional longer intervals, especially when the final doses of record were to be taken.