174 ARISTOTLE'S ANHOMCEOMERIA 



blood, and that a brain or anything analogous to a brain 

 was not found in other animals, except the cephalopods. * 

 Sensation he believed to be manifested more especially in 

 parts with blood, and, in one passage, which seems to be an 

 interpolation, it is stated that no part that is without blood 

 has sensation, t This passage must be read, however, in 

 conjunction with many other passages showing that he 

 meant that no part that is without blood or what is 

 analogous to blood manifests sensation, for his so-called 

 bloodless animals have sensitive parts. He recognized, 

 however, an apparent connection between sensation and the 

 presence of blood, and, reasoning consistently, concluded 

 that the brain, cold, bloodless, devoid of sensation, and 

 absent from many animals which manifested sensation, 

 could not be the sensory centre. 



So far, his reasoning, although based on false data, is 

 quite intelligible. There remain, however, a series of 

 statements which are not always consistent and are difficult 

 to understand. A strong argument in favour of the view 

 that the brain is the sensory centre is that it is connected 

 with the sense organs by what are now called nerves. Now 

 Aristotle concluded, and adduced arguments to support his 

 conclusion, that the brain was not connected with the sense 

 organs. He says : "It is clear from inspection and still 

 more from its being insensible when touched that the brain 

 has no unbroken connection {awex^ia) with sensory organs."! 

 Yet there are a few passages which suggest, and one which 

 seems to show, that he noticed such a connection, but he 

 did not admit that the connection was with the brain, but 

 with the blood-vessels about the brain. These passages will 

 next be discussed. 



He says : "Three ducts {'nopoi) extend from each eye to the 

 brain, the largest and the medium-sized one to the cere- 

 bellum, and the smallest, which is nearest the nose, to the 

 brain itself. The largest ducts lie side by side and do not 

 come into contact with each other, but the medium-sized 

 ones do so ; this is especially evident in fishes, for the 

 medium-sized ducts are nearer the brain than the largest, 

 and the smallest are very much separated from each other 

 and do not come into contact. "§ 



-'' P. A. ii. c. 7, 6526 ; H. A. iii. c. 14, s. 1, and in many other pass- 

 ages in his works. 



\P.A. ii. c. 10, 6566. + Ibid. ii. c. 7, 6526. 



§ H.AA.Q.;^, s. 4. 



/6 



