322 NERVOUS SYSTEM. 



The mode of connection between the cellular and the 

 fibrous elements of the nervous system has .already been 

 considered, and does not demand further mention. 1 We 

 will also pass over the amorphous matter, nuclei, myelo- 

 cytes, etc., found in the central nervous matter, as these 

 points possess little or no physiological interest. 



General Properties of the Cerebrum. By the general 

 properties of the cerebrum, we mean the effect, or the ab- 

 sence of effect, observed when the gray or white substance 

 is subjected to direct irritation. While some of the older 

 writers state that the brain is both irritable and sensible, 2 

 nearly all authorities, up to a very recent date, are agreed 

 that direct stimulation of the white or the gray substance of 

 the greatest part of the brain produces neither pain nor 

 convulsive movements. Among the numerous experimenters 

 who have exposed the brain and noted the absence of pain 

 and convulsions after direct stimulation of both the gray 

 and the white matter, may be mentioned Flourens, 3 Ma- 

 gendie, 4 and Longet. Longet states that he has exposed the 

 cerebrum in goats, and irritated both the white and the gray 

 substance by laceration, cauterization with potash and nitric 

 acid, the galvanic current, etc., with purely negative results. 6 

 In numerous experiments upon pigeons, we have invariably 

 observed the same insensibility and inexcitability of both 

 the gray and the white substance of the cerebral hemi- 

 spheres. 



1 See page 60. 



2 The most definite experiments on this point are those made by Haller and 

 Zinn, these observers noting, as it seemed to them, indications of pain, and 

 convulsive movements, immediately following mechanical irritation of the brain. 

 (HALLER, Memoir -es sur la nature sensible et irritable des parties du corps animal^ 

 Lausanne, 1756, p. 201, et seq.) 



8 FLOURENS, Systeme nerveux, Paris, 1842, p. 18. 



4 MAGENDIE, Lemons sur les fonctions et les maladies du systeme nerveux, Paris, 

 1841, tome i., p. 175, et seq. 



6 LONGET, Anatomic et physiologic du systeme nerveux, Paris, 1842, tome i., 

 pp. 642, 644. 



