GREEK BIOLOGY AND MEDICINE Aristotle's orders of animals, I quote the criti- cal resume of a recent authority: " The classification of birds is to this day in an unstable state. We may say that Aris- totle's grouping is substantially that which pre- vailed in scientific works till recent times and still remains as the popular division. His separation of the cartilaginous from the bony fishes, on the other hand, still stands in scien- tific works, and is a stroke of genius which must have been reached by means of careful dissection. . . . " For the Anaima [bloodless] or Inverte- brates even modern systems of classification are but tentative. There is an enormous num- ber of species, and after centuries of research naturalists still find vast gaps even in the field of mere naked-eye observation. Nevertheless, with the instinct of genius, and with only some 240 of these forms on which to work, Aristotle has fastened on some of the most salient points. Especially brilliant is his treat- ment of the Molluscs. There can be jqo doubt that he dissected the bodies and carefully watched the habits of octopuses and squids, Malacia as he calls them. He separates them too far from the other Molluscs grouped by [60]
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