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convolution cut transversely, it opens this from its base to its 

 summit. f 



A convolution. The centre (a) of the white 

 substance is seen opened by the impulse of air. 



Many fibres, especially those at the sides, are short ; while 

 others are longer, and this the more central they are. Hence 

 the prolongations and depressions of the surface of the cerebrum 

 or, in other words, the convolutions. The parts most developed 

 have the fewest convolutions ; and, in hypertrophy of the brain, 

 the surface is also more regular and smooth, the shorter fibres 

 approaching in length to the longer. The convolutions are sel- 

 dom quite vertical, and their white substance is thicker at their 

 lower parts, since there both the shorter and the longer fibres 

 exist. 



All the fibres are covered by cineritious pulpy substance at 

 their extremities. 



The origin of the cerebellum is in the corpora restiformia, ac- 

 cording to Gall. 8 They increase as they ascend ; and, entering 

 the cerebellum, penetrate to a mass of grey substance of a 

 somewhat rhomboidal form and with serrated edges, whence it is 

 styled corpus rkomboideum or dentatum. It is considered by Gall 



f Gall, from observing the mind of hydrocephalic patients to be little or not at all 

 impaired, was certain that Walter, Ackerman, and numerous others, were wrong, 

 who maintained that the brain was destroyed in the disease. Finding a female, 

 54 years of age, with her head greatly enlarged, he entirely supported her, as he 

 informed me, till she died, in order to prove the correctness of his opinion. He 

 examined her brain, and was thus led to discover the true nature of the convolu- 

 tions, and the operation of the distending fluid in hydrocephalus. Mr. Chenevix, 

 Dr. Spurzheim's friend, suppresses this (British and Foreign Quarterly, 1830), and 

 says that a fortunate accident occasioned the discovery (p. 10.). His article con- 

 tains other instances of inaccuracy and injustice towards Gall j but received Dr. 

 Spurzheim's sanction. By this discovery alone, Gall proved that those, who still 

 obstinately spoke of the brain as pulp, were wrong. Pulp would be washed or 

 blown away at the centre, and every where else, by the impulse of air or water, 

 and would not separate into two regular layers. Yet I recollect that in Edin- 

 burgh, in 1809, when I was studying, his anatomy and his assertion of the 

 fibrous structure of the brain were ridiculed as too absurd. 



8 Anat. et Phys.,\o\. i. p. 249. sqq. 



Z 2 



