660 FUNCTIONS OF THE CEREBRO -SPINAL NERVOUS SYSTEM. 



power of voluntary movement ; for although an animal maintains its bal- 

 ance, and can be made to move onwards, after the removal of the Cerebral 

 Hemispheres, and even after the removal of the Corpora Striata, yet if 

 either of the Thalami Optici be removed, the sensibility and power of vol- 

 untary movement are destroyed on the opposite side of the body, and the 

 animal consequently falls over to that side (Louget). If, instead of the 

 entire removal of one of the Thalami, an incision be made in it without the 

 previous removal of the Cerebrum, the animal keeps turning to one side in a 

 circular manner (evolution du manege): according to Longet and Lafargue, 

 this movement is directed in the rabbit towards the opposite side ; whilst 

 Flourens states that in the frog its direction is towards the injured side; 

 and according to Schiff 1 the destruction of the three anterior fourths of this 

 organ in the rabbit determines this movement towards the injured side, 

 whilst that of the posterior fourth determines the movement towards the op- 

 posite side. Brown-Sequard attributes the rolling movements in many of 

 these cases to certain muscles being in a state of spasm, in other instances to 

 vertigo. No mechanical irritation of the Thalami produces either signs of 

 pain or muscular movement ; and this fact might at first appear to negative 

 the doctrine that these organs are the ganglia of common sensation. 2 But 

 it must be borne in mind that the production of pain by mechanical injuries is 

 by no means a universal phenomenon in the case of the nerve-trunks which 

 minister to sensation, the olfactfre, optic, and auditory nerves being ex- 

 empted ; and it need occasion still less surprise, therefore, that a nervous 

 centre should be destitute of this kind of impressibility, which we have seen 

 to be wanting also in the Spinal Cord. 



528. The effects of lesions of the Corpora Striata are less distinctly marked. 

 It was affirmed' by Mageudie that there exists in them a motor power which 

 excites backward movement, and that a corresponding power of exciting 

 fonvard movement exists in the Cerebellum ; that these two powers ordi- 

 narily balance one another ; but that if either organ be removed, the power 

 of the other will occasion a continual automatic movement, the removal of 

 the Corpora Striata causing an irresistible tendency to forward progression, 

 whilst the division of the peduncles of the Cerebellum (according to him) 

 occasions the reverse movement. These assertions, however, have not been 

 confirmed by other experimenters. According to Louget, 3 Schiff, 4 and La- 

 fargue, 5 the results of removal of the Corpora Striata with the anterior part 

 of the Cerebral hemispheres, are for the most part negative; for the animal 

 usually remains in a state of profound stupor, although still retaining the 

 erect position ; and it is only when irritated by pinching or pricking, that it 

 will execute any rapid movements. No mechanical irritation of the Corpora 

 Striata produces either signs of pain or muscular movement. Bimlou-San- 

 dersou 6 has shown that by direct irritation of the Corpus Striatum, move- 

 ments of the muscles of the opposite side can be produced, and that there is 

 a certain correspondence in the groups of muscles that can thus be called 

 into play, and those that are excited by irritation of definite regions of the 

 intact cerebral hemispheres : on irritating the deepest part of the Corpus 



1 l'o-er and Wunderlieh's Archiv fur Physiol. Ileilkunde, lS4(i, # (ii',7. 



2 Nothnagel (Centralblatt., 1874. p 577) in n recent paper states that from numer- 

 ous experiments on Rabbits ho has satisfied himself 1. That the optic thalami have 

 nothing to do with the innervatmn of voluntary movements. '2. That after their ex- 

 tirpation, no disturbance of cutaneous sensibility can lie demonstrated. And 3. That 

 they appear to have a definite relation to the muscular sense 



8 Op. cit. 4 De vi motoria baseos Eneephali, Bockenhemii, 1S1~>. 



6 Essai sur la A'aleur des Localisations Encephaliques,etc., Tiicse Inaug., Paris, 1838. 

 6 Centralblatt, 1874, p. 513. 



