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Aristotle's Researches in Natural Science

Thomas East Lones



To the readers of Aristotle's zoological works, especially Books i.-iii. of his History of Animals, the question of the nature and extent of his dissections constantly presents itself. This question may be considered with respect to (1) the lower animals, and (2) Man, including the human foetus.

With respect to the lower animals, Aristotle often speaks of the necessity for ascertaining the structure and arrange ment of their parts by means of dissections. There are also many passages which clearly indicate the use of the dissecting-knife, e.g., parts of the description of the chamaeleon, of the eyes of the mole, and of the development of the chick in the egg. Again, some of his descriptions of the internal parts of animals, e.g., his description of the gall-bladder of the Pelamid, of the complex stomach of a ruminant, and of the aorta and its branches, indicate more than a laying open of the body of an animal and a casual inspection of its internal parts. There are also passages, e.g., those describing the movements of the heart and sides of a chamaeleon, after it had been dissected, and that referring to the movements of the heart after its removal from a tortoise, t which show that Aristotle vivisected some of the lower animals.

There are also statements which show that the dissections, if any, on which they were based were very carelessly performed, e.g., the statements that the wolf and the lion have only one bone in the neck and not separate vertebrae, and that the stomach of a dog or lion is not much wider than the intestine. Most of these statements were probably made by others and adopted by Aristotle without further examination, and, in any case, it would be unfair to estimate the value of his dissections by giving too much weight to such statements. His work on animals should be taken as a whole.

It is probable that Aristotle was taught dissection when quite young, for his father was one of the Asclepiads, an order of priest-physicians, who are said to have practised dissection and to have taught it to their children. He must have made many examinations of the internal parts of mammals, birds, reptiles, and amphibians, to which he often refers, and his extensive knowledge of many cephalopods, molluscs, echinoderms, and fishes, must have been the result of numerous dissections. A list of animals which Aristotle appears to have dissected will be found at the end of this chapter. It is probable, from the way in which adverbs of position, such as emprosthen and ypokato, are used in many passages, that Aristotle often dissected animals arranged in a vertical or at least highly inclined position.

With respect to human bodies, the chief question to be decided is whether or no Aristotle ever dissected one of these. In order to arrive at a conclusion, it is proposed to examine the evidence obtainable from Aristotle's writings, and then to examine the evidence furnished by the writings of other authors or by other sources of information.

After describing the external parts of the human body, Aristotle says that the internal parts are less known than those of other animals and that, in order to describe them, it becomes necessary to examine the corresponding parts of animals which are most nearly related to Man. He also states that the human stomach is like that of a dog, and is not much wider than the intestine, that the occiput is empty, and that the heart is above the lungs.

These passages clearly indicate that Aristotle never dissected a human body, and there are very few passages which suggest that he did so. His description of the position of the heart, has often been cited to show that he dissected the human body, but it is not by any means sufficient. On account of the importance of these passages in connection with the question of Aristotle's dissections, it will be necessary to discuss them at some length.

The heart, Aristotle says, is more to the left side in Man, being inclined a little away from the middle line, in the upper part of the chest, towards the left breast. This is substantially correct, for about two-thirds of the volume of the heart lies to the left of the median plane and its apex is directed towards the lower part of the left breast. The description may have been written, however, after an examination of the position of the heart of one of the lower animals, supplemented by an external examination of the part of the human chest against which the heart seems to beat. It is evident that the beat of the heart, usually per ceptible about three inches to the left of the median plane and in the fifth intercostal space, would suggest that the heart lies more on the left side of the chest. Galen says that it was on this account that the heart was believed to be on the left side ; he himself believed that the heart was in a central position.

Another passage sometimes cited to show that Aristotle dissected the human body is that in which he says that it is not without feelings of repugnance that we see blood, flesh, bones, blood-vessels, and other parts in the human body. This passage seems to cut both ways ; it is as much against as for the opinion that Aristotle dissected the human body.

It appears, therefore, that Aristotle's writings do not prove that he dissected the human body ; on the contrary, they contain many statements which suggest that he never did so. With respect to the human foetus, he seems to have dissected it, if only to a small extent. He says that if the human embryo, aborted after forty days, be put into cold water it becomes surrounded by a membrane, and that, if this be dissected away, the embryo appears to be of the size of a large ant, all its parts being visible and its eyes being large. Again, he makes some statements, e.g., that the human kidneys are lobulated, which are true of the human foetus.

Turning to the evidence obtainable from sources other than Aristotle' writings, it will be seen that there is a strong presumption against the probability that he ever dis sected the human body. Among the Greeks a feeling of repugnance against mutilation of the human body and against any neglect of speedy burial was prevalent. The execution of the Athenian commanders after the Battle of Arginusse, part of the charge being that they neglected to recover and bury some of the slain, and the attacks made at various time by orators against those who neglected to bury their deceased relatives, illustrate this. The agony of Antigone, the sad appeal of the shade of the unburied Patroclus, and the fervent wishes of many of Homer's heroes that their funeral rites might not be neglected accord well with the feelings of the Greeks. So strong were these feelings that it is unlikely that anyone could dissect a human body without exciting bitter feelings against himself. To meet this difficulty, some have held that Aristotle dissected the human body secretly. An assertion of this kind can neither be proved nor disproved.

Not many years after Aristotle s time, dissections of the human body were made at Alexandria, and Galen refers in many passages to dissections of this kind made by Erasistratus and Herophilus, about B.C. 280. These anatomists were followers of Aristotle, and their dissecting operations show that his oft-repeated advice about the importance of dissections did not fail to be effective. The anatomists of Europe were less fortunate than those of the Alexandrian Medical Schools ; Galen's dissections were mostly made on Barbary apes, and, at a much later time, the anatomists of the sixteenth and seventeenth centuries experienced difficulties in obtaining human bodies for purposes of dissection.

From the above it may be concluded that Aristotle dis sected many of the lower animals, and that, judged in relation to the anatomical knowledge of his time, his dissec tions were carefully performed. It may be said also that he dissected, to a small extent, the human foetus, but that he did not further dissect the human body.

In various parts of his works, one or more of the internal parts of about one hundred and ten animals are described in sufficient detail to suggest that he dissected them. It is practically certain that he did not dissect some of these, e.g., the hippopotamus and the crocodile, his knowledge of which seems to depend chiefly on Herodotus, but there are many for which definite information is given of so reliable a nature that it is fair to conclude that he dissected them. A list of these animals is given in the following table :


Grey Mullet
Red Mullet
Grass Snake
Star Gazer
Domestic Fowl

The inclusion of the elephant may cause surprise, but Aristotle's statements about it seem to justify its inclusion in the list.

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