362 INNERVATION. [CHAP. XI. 



We conceive that this view is far from admissible, on several grounds, 

 of which the following deserve particular mention. 



1. It is extremely questionable how far the sexual instinct ad- 

 mits of being separated from the emotions from those especially 

 which are clearly instinctive in their nature ; and, even if it were 

 separable from them, it seems scarcely of such importance, when com- 

 pared with the other instincts, as to need a separate organ of great 

 magnitude and of complex structure. If we compare it, for ex- 

 ample, with the instinct of self-preservation, as manifested in pro- 

 viding either for the wants of the body, or for defence against 

 assault, it certainly cannot be admitted to have a superior influence 

 in the animal oeconomy to this the most pressing of all. Yet it is 

 not pretended to assign a separate seat even to this. 



2. The nature of the generative instinct is scarcely such as to re- 

 quire in its central organ connexions so extensive as those possessed 

 by the cerebellum. It is not likely that this organ would be con- 

 nected with any other part of the spinal cord than that from which 

 nerves are derived to the organs of generation : nor is it conceivable 

 that an instinct like this should require for its exercise fibrous mat- 

 ter in such large quantity as exists in the cerebellum, taking its rise 

 from so great a surface of vesicular matter. 



3. The generative instinct is not so pre-eminently developed in 

 man as to account for the great superiority in size, as well as struc- 

 ture, of the human cerebellum over that of the lower animals, even 

 of the mammiferous class. On the contrary, it may be safely as- 

 serted that this instinct is much more powerful in the monkeys, and 

 also in the frogs ; in the latter of which the cerebellum is absolutely 

 very small, and especially so, relatively to the spinal cord and the 

 cerebral lobes. 



4. If the cerebellum be the seat of the generative instinct, it 

 ought to exhibit marked indications of wasting, in cases where the 

 genital organs have been mutilated ; or where they have decayed in 

 the natural progress of age. Yet the recorded cases of this nature 

 are by no means conclusive ; on the contrary, M. Leuret's remarkable 

 observations shew, that, in the gelding, the cerebellum is actually 

 heavier than in either the stallion or the mare. 



5. It does not appear, from pathological research, that the cere- 

 bellum has any peculiar influence upon the genital organs. Injury 

 or disease of that organ very rarely produces any effect upon the 

 penis ; but lesion of the medulla oblongata or of the spinal cord is 

 very apt to occasion a semi-erection of that organ. 



Of the Convolutions of the Brain. These, with the fibrous 



I 



