ROLLING AND TURNING MOVEMENTS. 633 



being. Death is nothing more than a permanent destruction of so-called 

 vital physiological properties ; and this occurs successively, and at different 

 times, for different tissues and organs. 



When it is seen that frogs will live for weeks, and sometimes for months, 

 after destruction of the medulla oblongata, and that in mammals, by keep- 

 ing up artificial respiration, many of the most important physiological acts, 

 such as the movements of the heart, may be prolonged for hours after de- 

 capitation, one can understand the physiological absurdity of the proposition 

 that there is any such thing as a vital point, in the medulla or in any part of 

 the nervous system. 



There is little to be said concerning certain ganglia and other parts of 

 the brain that have not yet been considered. The olfactory ganglia preside 

 over olf action and will be treated of fully in connection with the special 

 senses. The pineal gland and the pituary body, in their structure, present a 

 certain resemblance to the ductless glands, and their anatomy has been con- 

 sidered in another chapter. Passing over the purely theoretical views of the 

 older writers, who had very indefinite ideas of the action of any of the en- 

 cephalic ganglia, it can only be said that the uses of the pineal gland and 

 pituitary body in the economy are entirely unknown. The same remark 

 applies to the corpus callosum, the septum lucidum, the ventricles, hippo- 

 campi and various other parts that are necessarily described in anatomical 

 works. It is useless to discuss the early or even the recent speculations with 

 regard to the uses of these parts, which are entirely unsupported by experi- 

 mental or pathological facts and which have not advanced positive knowledge. 



ROLLING AND TURNING MOVEMENTS FOLLOWING INJURY OF CERTAIN. 

 PARTS OF THE ENCEPHALON. 



The remarkable movements of rolling and turning, produced by section 

 or injury of certain of the commissural fibres of the encephalon, are not very 

 important in their bearing upon the uses of the brain, and they are rather to 

 be classed among the curiosities of experimental physiology. These move- 

 ments follow unilateral lesions and are dependent, to a certain extent, upon 

 a consequent inequality in the power of the muscles on one side, without 

 actual paralysis. Vulpian has enumerated the following parts, injury of, 

 which, upon one side, in living animals, may 'determine movements of 

 rotation : 



" 1. Cerebral hemispheres ; 



" 2. Corpora striata ; 



" 3. Optic thalami (Flourens, Longet, Schiff) ; 



" 4. Cerebral peduncles (Longet) ; 



" 5. Pons Varolii ; 



" 6. Tubercula quadrigemina, or bigemina (Flourens) ; 



" 7. Peduncles of the cerebellum, especially the middle, and tho lateral por- 

 tions of the cerebellum (Magendie) ; 



" 8. Olivary bodies, restiform bodies (Magendie) ; 



