436 BIOLOGY. [BOOK vi. 



by reasoning, by a relative estimate of the motive, becomes a 

 volition ; whence the will of the psychologists. 



But behind all this labyrinth of psychical phenomena there 

 are simply reflex acts, transformed sensations and impressions. 

 Moreover, all this mental labour, of which the excessive compli- 

 cation in man has so long defied observation, is simply the result 

 of the special properties of the nervous tissue. In effect, every 

 sensation is accompanied by an elevation of the temperature of 

 the nerve and a disturbance of its electric condition, by a 

 negative oscillation of the nervous current. Besides, in order 

 that it may take place, a considerable time is necessary, corre- 

 sponding to an elevation of temperature in the cells which are 

 its seat, 1 coinciding with a sur-oxydation, a waste of the sub- 

 stance of those cells which eliminate a much greater quantity of 

 phosphates, &c., &c. 2 



Finally, comparative anatomy, anthropology, pathological 

 anatomy furthermore lend their valuable co-operation to physio- 

 logy ; they show us that the moral and intellectual faculties are 

 completely in subjection to the nervous centres ; that they follow 

 with docility their variations, more or less, to better or to worse ; 

 that they develop, diminish, or change with them. The pheno- 

 mena of consciousness are, then, throughout the animal kingdom, 

 not excepting man, functions, acts of the nervous cell. Upon 

 this point doubt is impossible. 



But we are not confined to this simple declaration. A young 

 Italian physiologist, Dr. Mosso (of Turin), has just opened up to 

 experimental psychology a track altogether new, by providing it 

 with an apparatus which may aptly be called a psychometer. 

 Our readers will surely be grateful to us for giving here a 

 summary of the still unpublished work of Dr. Mosso. 



It has long been known that there was a certain connection 

 between the contractility of the vessels, especially of the capillary 

 vessels, and certain agitations of the nervous centres, for example, 



1 Schiff, Archives de Physiologic, t. II., 1870, and Lombard, id., t. II., p. 670. 

 3 Byasson, loc. cit. 



