Chapter VI

"All things are but altered, nothing dies,
And here or there the unbodied spirit flies."

DRYDEN.

The most universal character impressed on all created things that sense allows us to recognize, or philosophical inquiry to demonstrate, is "change."

While nothing is more certain, few things pass less observed; or, when first announced, more stagger conviction.

An old man sees the yew-tree of his boyish days apparently the same. Gilpin tells us "eight hundred years is no great age for an oak[17]!"

The cliff which we left "beetling" seems to beetle still; mountains appear to be everlasting; yet, were seas and rivers to disclose even a small part of their mission, the Danube or the Volga might tell of millions of tons of soil carried from higher levels to the Black Sea and the Caspian. Animals, too, are mighty agents in recording the mutability of the matter of the universe. Coral Reefs, never spoken of in smaller terms than miles and fathoms, are the vast ocean structures of countless millions of animalcules, which serve, as it were, to link together the two great kingdoms of organic nature—the animal and vegetable creation. The microscopic geologist informs us of whole strata, well-nigh entirely composed of the silicified skeletons of insects. Sir Charles Lyell further impresses on us the reality of continual change, by referring (and, as it would appear, with increasing probability) even the stupendous changes demonstrated by geology to the agency of causes still in operation.

Animals, however, besides the curious structures which they combine to contribute, are individually undergoing constant change. Man is not only no exception, but he is a "glaring" example.

The whole human race are in hourly progress of mutation. "In the midst of life we are in death," is a truth to which physiology yields its tribute of illustration. Every moment we are having the old particles of our bodies silently taken away, and new materials as silently laid down. Surrounding influences, as air, moisture, temperature, &c. which, during life, are necessary to existence—the moment the breath leaves us, proceed to resolve the body into the elements of which it was composed. In all cases, change may be regarded as the combined result of two forces: the force acting, and the body acted on—that is to say, of certain external agents and certain forces inherent in the thing changed.

Animals are no exceptions to this view, and diseases are amongst a multitude of other exemplifications of it; but, in order to distinguish these more clearly, it is desirable that we should be familiar with those more ordinary changes in the body which are constantly going on; and to some of these were Abernethy's early investigations directed.

In proceeding to give some account of his works, we must be necessarily more brief than a scientific analysis would require.

To do him full justice, it would be necessary to republish his writings, with appropriate commentaries. We shall hope, however, to do enough to relieve his memory from some of the numerous misconceptions of his principles and opinions; and to endeavour to show his claims to the respect and gratitude of posterity.

In everything Abernethy did, we find evidence of the acuteness of his mind, and his general qualifications for philosophical research.

His lectures had gradually attracted an increasing number of students; and he seems, about 1791, to have been desirous of prefacing his lectures on Anatomy by discussing the general composition of Animal Matter.

The rapid advance of chemistry had given a great impetus to this kind of investigation. Abernethy was not only well up in the chemistry of the day, but also not unskilled in the manipulatory application of it; and he felt interested in observing the great diversity of substances which appeared to be made up of similar elements. Boyle has recorded a vast number of facts, many of which would even now well repay a thoughtful revision; and Fordyce was certainly one of our most philosophical physicians.

Boyle had grown vegetables in water and air only, and found they produced woody fibre. Fordyce found that gold fish, placed under similar conditions, not only lived, but _grew_. Abernethy's experiments had for their object to inquire how far organized bodies (animals and vegetables) were capable of deriving their various structures from similar simple elements.

He grew vegetables on flannel, wetted from time to time with distilled water; and then, analyzing them, compared the results with those of the analysis of vegetables grown in the ordinary manner.

Other curious experiments consisted in pouring concentrated acids on vegetable structures, with a view to dissolve any alkali or iron which they might contain, and then analyzing the vegetables so treated.

He now found, in the burnt vegetable, lime, iron, &c. which, had they been free to combine, should have been taken up by the acid to which he had subjected the vegetable before he analyzed it; but he found neither in the _acid_, whilst both were discovered in the _vegetables_.

He also inquired whether tadpoles and leeches would live when kept only in distilled water, with the admission of air. For example, he placed twelve leeches in two gallons of distilled water, They weighed, in all, twelve scruples. In three months, two had died, but the remaining ten weighed twelve scruples, showing that they had _grown_. He next inquired whether vegetables, grown in air and distilled water, would admit of further conversion into the structure of animals; and, for this purpose, he fed rabbits on vegetables so reared. His rabbits appear to have eaten about six plates at a meal of young cabbages thus reared on flannel wetted with distilled water.

He also experimented on eggs, both before and at the time of incubation.

He wished to ascertain the quantity of lime in the chicken and the egg, respectively; and whether any of the lime was absorbed from the shell, which it appeared not to be.

It is curious to observe the time and labour he gave to these experiments; they evince a very perfect knowledge of the chemistry necessary; whilst the circumstances calculated to interfere with or obscure the conclusions from them are judiciously and clearly stated.

Many of his remarks, as well as the ingenious suggestions with which they are interspersed, exemplify the caution with which he reasoned. In speaking of his experiments on leeches and tadpoles, many of which latter had become perfectly developed frogs, he says: "The experiments which I made on this plan (in vessels of distilled water, covered with linen) were made in the summer, when to prevent vegetation was impossible; and, on the other hand, when the vessels were covered over, even leeches died. In the winter, vegetation might cease; but then the torpid state of the animals would render the experiments inconclusive."

He reduced an equal number of eggs and chickens (at the time of incubation) to ashes; sometimes in crucibles, sometimes in retorts. On the ashes he poured some distilled water, and ascertained the salts (as lime, &c.) contained in them. In some experiments, the quantity of these found in the ashes of the chickens greatly exceeded that found in the ashes of the eggs. In other experiments, the quantities were equal.

In some of his experiments, after using the best chemical tests for detecting iron, lime, and the salts, and then washing the residue with distilled water, he burnt it in a crucible, and found more lime and iron; on which he makes the following remarks, which suggest what we apprehend, even at this time, is a very necessary caution:

"This circumstance proves to me that the substances found in the ashes of burnt animal matter do not formally exist in the mass before its destruction, but are only new distributions of the same ultimate particles which, under their former mode of arrangement, made the animal substance; but which, being driven asunder by the repulsive power of fire, are left at liberty to form other modifications of matter." Page 97. Just what happens when animal matter is burned, in the formation of ammonia, by the union of the nitrogen and hydrogen then set free.

He investigated, also, the question of how far the results of the decomposition of animal matter would be identical, if the analyses were conducted by heat, or by putrefactive decomposition. In this experiment, he selected blood; and he found that blood which had been allowed to putrify yielded _a much larger quantity_ of iron and lime.

The whole of the experiments are very suggestive, and full of thought; and not only indicate very forward views of the elementary constitution of organic and inorganic matter, but also moot questions which have not lost any of their interest by the most recent investigations. He concludes by observing that he had undertaken these experiments for the reasons already assigned, and because he had imbibed the idea that the _ultimate particles of matter were the same_.

He remarks that the progress of chemistry had not been applied, in every respect, to the best purpose; that men's views were becoming _contracted_ by being directed to _individual_ objects; and that they had ceased to contemplate the beautiful and extensive subject of matter and its combinations; and he complains that even Fourcroi, Lavoisier, and Chaptal, either avoid the subject, or do not sufficiently consider it. We must recollect this was said before Sir H. Davy had made his splendid discoveries. Abernethy, after observing that he hopes his experiments will induce others to investigate the subject, concludes thus:

"I know not any thought that, on contemplation, can so delight the mind with admiration of the simplicity and power evident in the operations of the Creator, as the consideration that, by different arrangement and motion of singular atoms, He has produced that variety of substances found in the world, and which are so conducive to the wants and gratification of the creatures who inhabit it."

DISSECTION OF A WHALE.