1/6 • Notes, ii. lo. 



none at all. Similarly, though he knew there was some blood' in the lung of oviparous 

 vertebrates, he often speaks of it as bloodless, because the amount was insignificant, as 

 he thought, when compared with that in the lung of a mammal (iii. 6, Note lo). 



So also I would explain the third error, that the brain is cold to the touch. He 

 very possibly found the basis for this Jiotion, which was essential for his interpretation 

 of the brain's function, in the brain of a fish or tortoise ; for it is extremely unlikely 

 that he even examined the brain of a warm-blooded animal while the warmth of life 

 was still in it. We must remember that the art of dissection was in its infancy, and 

 that even much later, in Galen's time, the mechanical difficulty of removing the calvaria 

 was such, that Galen recommends his readers, because of the imperfection of their 

 yistruments, to get from the butcher a head in which the brain was already exposed. 

 Nor must we neglect to make full allowance for the constant results of preconceived 

 theories. Every experimental physiologist must be painfully conscious how they thwart 

 his most honest intentions, and put a film between his eyes and his object. Aristotle 

 would have been more than human to have escaped this source of error. 



19. What A. precisely meant by the passages, or channels, or pores (irSpoi) upon 

 which the sense-organs are placed, is very problematical. Meyer {T/iier/mnde; p. 42S) 

 takes him to mean the blood-vessels, .mainly because" this accords with the statement 

 {D. G.-v. 2, 2) that all these irSpoi pass to the heart. There is no doubt that vSpoi 

 is often used by A. to designate blood-vessels ; but I think it plain, that A. is here 

 speaking of something which is more distinctive of the sense-organs than the presence of 

 vessels, which they share with the rest of the body. Frantzius, following Schneider, 

 has no doubt that nerves are meant, and thus A. would have to be credited with the ana- 

 tomical discovery of the nerves of sense, or at any rate of the optic, auditory, and olfactory 

 nerves. ' I have little doubt that on several occasions where A. uses the term irSpos, 

 the thing he is speaking of is a nerve, as in Z>. G. ii. 6, 33, where he speaks of either 

 the optic nerve, or of some other nerve going to the eyfe, under this title. And agaiij in 

 this passage : " Cases have occurred, when men have been wounded in battle in the head, 

 in such a way that the irSpoi of the eye have been severed ; a sudden darkness has then 

 come over them, as though a lamp were extinguished, etc." (De Sensu, 2, 17); and 

 perhaps, though I am very doubtful, in the obscure passage in the Hist. An. (i. 16, 6). 

 Moreover, that he had seen the optic nerve is certain from his statement {H. A. ii. Ii, 9) 

 that the eye of the chamseleon is continuous* with the brain. Were he then only 

 speaking of the eye, it might fairly be admitted that its v6poi were its nerves ; and it 

 may be noted that in after-times Tr6poi was the term specially applied by Herophilus to 

 the nerves of the eye {Galen, De Usu part. iii. 12). But A. uses the same expression for 

 the other sense-organs. "All the sense-organs have it6poi connecting them with the 

 heart" (Z>. G. v. 2, 2). Now it seems to me exceedingly improbable that A. knew of the 

 olfactory or auditory nerves. He clearly looks on the nerve of the eye as something very 

 peculiar, and explains its presence by the eye being made of the same substance as the 

 brain, and therefore requiring a communicating passage by which the cold fluid of this 

 latter may pass into it (Z?. G. ii. 6, 33). This is quite incompatible with the notion that 

 he had seen similar leipoi. with similar substance going to the very dissimilar ear and nose. 

 Indeed, he expressly says that the ■n6po\. of these two sense-organs are full of " innate spirit," 

 that is, of something physically like air (ii. 16, Note 11), and that they communicate with 

 the air outside the body. The way moreover in which he speaks of the auditory irfipos 

 in the text shows that he means something of the same character as the external meatus. 

 "There is a idpoi which leads back again from the ear to the hinder part of the head." 

 The same notion is apparent in what he says of the olfactory organs of fishes (cf. Note 13). 



