2i 



2d. Turning and Rolling produced by an injury to the Medulla 



Oblong ata. 



M. Magendie (Precis Ele'm. de Physiol. Paris, 1836, t. 1, p. 

 414) says : " Having raised up the cerebellum, I make a 

 section perpendicularly to the surface of the fourth ventricle and 

 at three or four millimetres from the median line. If I cut on 

 the right, the animal will turn on the right side ; if I cut on the 

 left, it will turn on the left side." 



If we suppose a plane cutting the medulla oblongata transversely 

 at the distance of nearly two lines before the nib of the calamus 

 scriptorius, the posterior face of the medulla oblongata will be 

 divided into two parts : one before that plane, which I will call 

 superior, and the other behind, or inferior. 



Now, every puncture on that superior part produces turning 

 or rolling on the side which has been punctured. The slightest 

 puncture on the processes cerebelli ad medullam oblongatam is 

 able to produce a violent and very rapid rolling. As long as the 

 animal lives after the operation, it rolls or it turns at each time it 

 tries to walk. 



When (as Dr. Martin-Magron and myself have discovered) a 

 deep section is made on the inferior part of the posterior face of 

 the medulla oblongata, before the nib of the calamus scriptorius, 

 turning is produced on the side of the body opposite to the punc- 

 tured side of the medulla. A rabbit, which has lived thirteen 

 days after the operation, had still the circulatory movement a 

 few hours before dying. Nevertheless, sometimes the animal 

 could walk nearly straight during a few seconds. 



3d. Turning Produced by a Puncture or a Section of the 

 Acoustic Nerve. 



Flourens has discovered that, after the section of the semi- 

 circular canals, turning sometimes takes place. 



I have found all the facts he relates about this subject perfectly 

 right. It was interesting to know if a puncture or the section 

 of the auditive nerve would produce turning. As it was impos- 

 sible to operate on that nerve in mammals, I have experimented 

 on frogs. In these amphibia it is easy to find the nerve and to 

 act upon it. I have found that after a puncture or a section on 

 the trunk of the nerve, the animal begins instantly to turn. As 



