326 Dr. Macartney on the Structure of the Brain in the Chimpanzee and 



of structure are observed in the brains of different rational human beinffs. I 

 have found many deviations from the ordinary structure in subjects, without being 

 able to ascertain what peculiarities of character belonged to them when alive ; 

 but in one instance, of a deaf and dumb person, the white strice of the fourth 

 ventricle (with which the auditory nerves communicate) were imperfectly formed, 

 were not subdivided, and did not unite with each other. If, therefore, we can 

 ever arive at correct notions of the functions of the brain, it must be by careful 

 dissections of the interior parts of the cerebral organ, and by ascertaining the 

 correspondence between the minute structure, and the endowments and disposi- 

 tions of the different individuals ; taking into account, at the same time, the influ- 

 ence of the various organs of the body, instead of ascribing to certain parts on 

 the surface of the brain, distinct and often opposing faculties, as Gall and Spurz- 

 heim have done. 



It seems to be particularly absurd to suppose that the cerebellum, a part evi- 

 dently as highly organized, and of as much importance as the cerebrum itself, 

 should be designed to produce merely the sexual instinct. In animals that have 

 the lateral lobes of the cerebellum very small, or who want them altogether, this 

 instinct is stronger than in man. In those instances which are known of the absence 

 of a part, or one lobe, or the whole cerebellum, no want of the venereal appetite 

 existed ; and a case is related of a person in whom the sexual desire was so ungo- 

 vernable, that mechanic restraint became necessary ; and it was found, after death, 

 that both lobes of the cerebellum were wanting in this person. In animals that 

 propagate only at particular seasons of the year, the testicles and ovaries are sin- 

 gularly developed at those periods, and afterwards decline, while at the same time 

 no change takes place in the cerebellum. The abolition of the sexual instinct, 

 by the extirpation of the testes, or of the ovaries, puts it beyond all doubt that this 

 impulse does not originate in any part of the brain. 



It would appear that all instincts depend upon the condition and state of feel- 

 ing in those organs with the functions of which they are immediately connected ; 

 thus, the maternal instinct (at least in mammiferous animals) is in a great mea- 

 sure the result of the tension of the mammary glands. As soon as this is removed, 

 by the absorbents carrying off the milk, quadrupeds lose all care and anxiety about 

 their young. The cerebral organ would, perhaps, of all others, be the most unfit 

 for the generation of instincts. The brain is destined to direct or control instinc- 



