Aristotle on youth & old age, life & death and respiration / translated, with introduction and notes by W. Ogle.

  • Aristotle
Date:
1897
Catalogue details

Licence: Public Domain Mark

Credit: Aristotle on youth & old age, life & death and respiration / translated, with introduction and notes by W. Ogle. Source: Wellcome Collection.

    54/184 (page 42)
    largest, the most richly supplied with blood, and has the most minutely divided air-passages, so as to present the amplest surface of contact. These ' conditions of perfec- tion ' were fully recognised by Aristotle, who correctly states that they are best fulfilled by the lungs of mammals, the lungs in the other pulmonate vertebrates being com- paratively small and bloodless, and of a more pronounced spongoid character (o-oyLK^oy), or of membranous consistency (v/jLsv(oS7]9)y with large insterstices in their substance like the bubbles in foam.^ These differences in the perfection of the lungs of animals, as also corresponding differences in the development of the gills of fishes, Aristotle supposed to be correlated with differences in their vital heat, and therefore to supply a measure of their position in the scale of being. For in proportion to the vital heat would be the necessity of provision for its regulation. Having discussed at some length Aristotle's account of the structure and use of the lungs, it will be unnecessary to give much time to his views concerning the gills. That Aristotle examined these organs with some care is shown by the numerous observations he makes as to the differ- ences they present in different fishes in regard to their position and number, their singleness or doubleness, and the presence or absence of an operculum.^ But as to their form and structure he says nothing. All he tells us is that a branch goes to each gill from the blood-vessel that issues from the anterior end of the heart, that is from what we know as the bulbus arteriosus and branchial artery.^ As to the process itself, the account he gives is that the refrigeration, which in pulmonate animals is effected by air, is in fishes effected by water, which is taken in at the mouth and discharged through the branchiae at the gill openings. The alternate expansion and contrac- tion of the branchial apparatus which determine this current of water is, he says, brought about by the same > Cf. note 44.