FUNCTIONS OF THE SENSORY GANGLIA. 661 



Striatum, the animal opened its mouth, and alternately thrust out and re- 

 tracted the tongue. 1 



529. When the fibrous tracts which connect these ganglionic masses with 

 the Medulla Oblougata, and which are commonly (but erroneously) desig- 

 nated as the Crura Cerebri, are completely divided, the result, as might be 

 anticipated, is the annihilation of sensibility and of the power of voluntary 

 movement in the body generally. 2 When, however, the Crura. Cerebri of a 

 rabbit are not completely divided, but one of them is partially cut through 

 a little in front of the Pons Varolii, the animal is said by Longet and Schiff 

 to exhibit a constant tendency to turn towards the side opposite to that of 

 the lesion, so that it performs the circular evolution du'manege ; the diameter 

 of its circle of movement being smaller, in proportion as the incision ap- 

 proaches the edge of the Pons. But if one of the Crura be completely 

 divided, the animal then falls over on the opposite side ; the limbs of that 

 side being paralyzed to the influence of the Eucephalic centres, though they 

 may be still caused to exhibit reflex motions. Hence it appears that the 

 circular movements which are performed after incomplete lesions of the 

 Crus Cerebri and Thalamus Opticus of either side, are due to the weakening 

 of the sensori-motor apparatus of the opposite side, whereby the balance of 

 the muscular actions of the two sides is destroyed. Nearly the same results 

 have been obtained on this point by Longet, Lafargue, and Schiff. Afana- 

 siefF 3 found that in the course of two or three weeks an animal in which one 

 of the cerebral peduncles had been divided, was able to run straight forward. 

 The section causes complete paralysis of the oculo-niotorius on the same 

 side, and imperfect paralysis of the facial nerve on the opposite side. It 

 also produces diminished sensibility of the body and head, and contraction 

 of the arteries, which lasts for 10 or 15 days, and is more marked in the ear 

 of the same side. At the moment of section the blood-pressure is increased, 

 and the pulse slowed, and in half an hour the temperature of the body falls 

 3 F. Division of both peduncles destroys the power of voluntarily re- 

 laxing or constricting the sphincter ani, as well as of relaxing the constrictor 

 u re three. 



530. Considerable importance is attached by some Physiologists to the 

 part of the Eucephalon known as the Tuber Anmilare, to which the name of 

 Mesocephale has also been given. This is not altogether synonymous with 

 the Pons Varolii, as some Anatomists have represented it ; for, while the 

 latter consists of transverse fibres which form the commissure between the 

 hemispheres of the Cerebellum, surrounding and passing between the longi- 

 tudinal fibres of the Sensory and Motor tracts which constitute the Crura 

 Cerebri, the Tuber Anuulare (which exists in animals whose Cerebellum 

 has no hemispheres) is a projection from the surface of the proper Medulla 

 Oblougata, containing a considerable nucleus of vesicular matter. M. 

 Brown-Sequard* has drawn the following conclusions respecting the func- 

 tions of this part of the Encephalon, chiefly based on pathological evidence: 



1. That the restiform bodies and their prolongations into the Pons, and 



1 Hitzig (Centralblatt, 1874, p. 548) criticizes Dr. Sanderson's statements. 



2 It is considered by Longet that these functions are not completely destroyed, be- 

 cause the animals on whom this operation has been performed still retain some power 

 of movement, and respond by cries to impressions that ordinarily produce pain. 

 There is no proof, however, that such actions are other than " excito-motor ;" they 

 certainly cannot in themselves be admitted as proving the persistence of conscious- 

 ness in the lower segment of the Cerebro-Spinal axis. (See Brown-Sequard, Central 

 Nervous System, 1860, p. 225; and Schroeder v. d. Kolk, Syd. Soc. Trans., 18-59, 

 p. 76.) 



1 Wien. Med. Wocbens., pp. 137, 153, 169, and 185. 

 4 Journ. de la Physiol., vol. i. p. 7t52 ; vol. ii, p. 121. 



