1 82 Notes, ii. i6. 



or the other, right or left as Ihe case may be, and sleeps in that position. Its hind 

 legs it bends in the same way as a man" (Z^. A. iL i, 9). The reader will find an- 

 interesting discussion explaining the probable source of the ancient belief in this 

 matter in TennettCs Ceylon. 



8. In the present day the term " respiration " is commonly used to designate the 

 process by which a gaseous interchange is effected between the blood and the medium, 

 be the organs in which the process is wrought what they may. But A. uses it exclusively 

 for the act of inspiring and expiring air from lungs. The purpose of this was, he 

 thought, to produce cooling. But, though a similar result was obtained by the water 

 acting on the gills, he did not apply the term respiration to this latter process, not 

 crediting the existence of air in water. This was known to Galen, who supposed 

 {De Usu part. vi. 9) that the air got into the gills through little holes, which, though 

 large enough to admit air, were yet too small to admit water. As to the reasons why 

 A. supposed fishes to smell by the gills) cf. Note 10. 



9. It is of course of the Cetacea that A. is speaking. It must be an accidental slip 

 that makes him include them here amongst animals that do not breathe ; for he 

 frequently mentions the fact that they have lungs. The blowhole corresponds 

 anatomically to the nostrils. It is however very doubtful whether any of the 

 Cetacea can smell. Dolphins and porpoises at any rate must bfe unable to do so ; 

 for they have no olfactory nerves. 



10. Frantzius gives up the hypozoma as unintelligible. There is however no doubt 

 what A. means by it. It is the waist or border-line between thorax and abdomen ; 

 which in insects is especially distinct. Nor is there any difficulty in understanding why 

 A. located the sense of smell in this part of an insect's body. He says that the part 

 below this hypozoma is that which in insects functionally corresponds to the lungs or 

 gills of higher animals ; that is, is the organ through which cooling is produced. This 

 is brought about by there being in this region a portion with a membranous covering, 

 much thinner than the rest of the integument, so as to allow of the escape of heat. 

 The cooling is effected not by the external air, but by the fanning motions of the internal 

 "innate spirit." The motions are visible in the alternate rise and fall of the part of 

 the body in question. Not only is this thin membranous part the organ of refrigeration ; 

 but it also corresponds to the lung in another way. It is the organ of sound ; and thus 

 it is that there is a special cleft in this part in those Cicadae that are said to sing, but no 

 such special cleft in those that do not sing (ZT. A. iv. 9, 3 ; De Som. 2, 17). 



It is plain that A. is speaking of the so-called drums of the Cicadae, which are placed 

 on the first segment of the abdomen, that is directly below the hypozoma, and which are, 

 as he rightly says, the organs by which these insects produce sounds. Though he 

 describes these rightly as specially belonging to the Cicadae, yet he seems to think there 

 is something of the same sort in all insects that make buzzing sounds, as bees, wasps, 

 and the like, probably alluding to the thinner portions of integument which lie between 

 the successive segments of the abdomen. That these " drums", serve as the equivalent 

 of the respiratory organs of higher animals is incorrect ; yet the notion was by no means 

 an unnatural one. The motions of the abdomen to which A. refers are of course the 

 alternate contractions and dilatations by which air is exjielled and inhaled, from and 

 into the tracheal system. 



We can now see why A. supposed the olfactory sense of insects to be located in the 

 hypozoma or rather in the part below it. It was the same reason as that which made 

 him believe that the gills of fishes (cf. ii. 10, Note, 13) and the blowhole of Cetacea were 

 organs of smell ; the reason being that gills, blowhole, hypozoma, corresponded to the 



