134 CRANIAL NERVES. 



developed in those animals which possess this sense acutely. 

 M. Bernard has, however, thrown some doubt on the question 

 whether these are the only nerves presiding over this sense. 

 His objections are principally founded on the case of Marie 

 Lemens, in whose brain the autopsy showed an entire ab- 

 sence of olfactory lobes. Singularly enough, the testimony 

 of those most intimate with this woman went to show that 

 she disliked very much the odour of tobacco ; that she was 

 fond of flowers, and smelt them like other people ; that she 

 worked in a kitchen, and smelt and tasted the dishes in the 

 usual manner. And, lastly, that in her last illness she 

 constantly complained of the disagreeable odour of her 

 abundant perspirations. Standing alone as this case does, 

 and being, moreover, a congenital infirmity, too great im- 

 portance ought not to be attached to it, and stronger 

 evidence must be adduced before it can be acknowledged 

 that the fifth, the only other nerve which sends branches to 

 the nose, assists in any degree in the appreciation of odours. 

 OPTIC NERVES. The second pair of nerves consist of 

 white bands, which, from the corpora striata, corpora geni- 

 culata, and especially the corpora quadrigemina, pass 

 downward round the outer side of the crura cerebri, turn 

 forward and inward to decussate with each other in the 

 median line, and proceed through special bony canals to 

 their respective eyeballs. Their expansion in the eyeball 

 (retina) contains numerous ganglionic cells, and must be 

 considered as a true nerve centre. At the point of decus- 

 sation, some fibres pass from the cord on the one side to 

 that proceeding to the opposite eye ; some pass into the 

 cord which proceeds to the eye on the same side ; some 

 pass into the opposite cord, in which they proceed back- 

 ward to the brain ; and a fourth set, coming from the eye 

 on the one side, crosses over and reaches the opposite eye 



