YITAL APPARATUS OF SMELL. 227 



animal machine, and which are intended to pro- 

 vide a large surface within a limited space. In 

 order to increase the extent of this membrane as 

 much as possible, it is thrown into a -multitude 

 of minute plaits which radiate from a central 

 point and have a very elegant appearance. From 

 the back of the olfactory chambers there proceed, 

 as we have already stated, two nervous cords, 

 which conduct the impressions received by the 

 mucous membrane to the brain. 



The vital apparatus of smell, like that of sight, 

 consists of two round masses or lobes of nervous 

 substance, which occupy the front of the brain, 

 and preside over the manifestation of the olfactive 

 faculty. They are inferior in size to the optic 

 lobes, though often as large as the hemispheres of 

 the brain. We are thus supplied with conclusive 

 evidence of the possession by fishes of a power of 

 smell. The mechanical and the vital portions of 

 the apparatus, with the conducting nerve from the 

 former to the latter, are complete ; the only ques- 

 tion which requires solution is the degree of the 

 sentient power. The vital apparatus being large 

 would be an argument in favour of a vividness of 

 perception; but the small mechanical portion, 

 and especially the absence of a stream of water 

 through the olfactory chambers, leave the organ 

 imperfect. On these grounds, we should be in- 

 clined to give the faculty of smell a position next 



Q2 



