22 



long as the frogs live, after a puncture of the acoustic nerve, they 

 turn ; but the circle of turning is much smaller a short time 

 after the operation than afterwards. I have kept such frogs 

 for months. 



4th. On a New Mode of Turning. 



I have found a mode of turning which has altogether some of 

 the characters of turning and of rolling. 



In the circulatory movement called turning (mouvement de 

 manege), the body of the animal is bent on one of the lateral 

 sides. It has the shape of an arch, and this arch is generally a 

 part of the circumference described by the animal when turning. 

 The smaller the radius of that arch, the smaller is the circle of 

 turning. 



In the new mode of turning I have found, the body of the 

 animal is not bent, and when it walks it moves laterally, 

 instead of going forwards. In turning it describes a circle, but 

 the longitudinal axis of its body, instead of being then a part of 

 the circumference, is a part of a radius, so that its head is at the 

 circumference, and its tail towards the centre of the described 

 circle. 



That mode of turning has been executed by animals on which 

 the quadrigeminal tubercles and the pons varolii, on one side, 

 had been punctured by a pin. One of the eyes was convulsed ; 

 the other was in its normal condition. The convulsed eye was 

 the right one, and the tubercles punctured were those of the 

 left side. 



5th. On the Causes of Turning and Rolling. 



I have not room enough to show that the theories of Magendie, 

 Flourens, Henle, Lafargue and Schiffare contradicted by a great 

 many facts. I will only present the following remarks : 



1st. As the slightest puncture of certain parts of the encepha- 

 lon is sufficient to produce turning or rolling, it is evident that 

 those rotating movements do not exist in consequence of an 

 hemiplegia, as Lafargue, Longet and SchifF believe they do. 

 Another reason is that every degree of hemiplegia exist in man 

 without being accompained by turning or rolling. Besides, these 

 phenomena have been observed in persons who had no paralysis 

 at all. 



