G. GENERAL NATURAL HISTORY AND ZOOLOGY. 287 



of a frog, the aorta of which had been tied, and the animal 

 placed in the position indicated above, M. Prevost has pro- 

 duced anaesthesia in the head of the animal alone, leaving: the 

 functions of the spinal marrow unaffected ; but upon subse- 

 quently untying the aorta, the frog returned to the normal 

 condition, which proves that the chloroform in this experi- 

 ment has acted only as a simple anaesthetic, and not as a 

 caustic, which destroys the brain, leaving the frog in the con- 

 dition of a decapitated animal. M. Prevost therefore thinks 

 he is entitled to conclude from his experiments that chloro- 

 form produces anesthesia in the nervous centres only in the 

 portions with which it is directly in contact, and that it does 

 not act at a distance, as M. Bernard supposed. Mem. Soc. 

 Physique de Geneve, XXL, 1870, 350. 



ORIGIN OF NERVE FORCE. 



Mr. St. Clair Gray has lately published a paper upon the 

 origin of nerve force, which he illustrates by what he consid- 

 ers to be a new source of electricity. In the course of some 

 of his experiments he prepared a cell containing a solution 

 of caustic potash, in which sticks of phosphorus and sulphur 

 were placed ; and within half an hour he found that, while 

 the sulphur was apparently unaffected, the phosphorus was 

 reduced to an oily mass at the bottom of the cell. After a 

 time, however, it was ascertained that several salts of potassi- 

 um occurred in the solution, and that the sulphur at the point 

 of contact with the phosphorus had sustained a considerable 

 loss of substance. Similar conditions being found at the end 

 of three months, the phosphorus still fluid, and the sulphur 

 having, a continued waste, the amount of electricity gener- 

 ated was tested by Thomson's electrometer, and the electric 

 motive force was discovered to be 162; and as a Daniell 

 cell only gave 120, the difference in favor of the new cell 

 was 42. The constancy of this battery was shown by its 

 continuing to work steadily after the expiration of several 

 months. 



Acting upon these hints, Ml*. Gray proceeds to suggest a 

 new hypothesis in regard to the origin of nerve force ; and, 

 starting with the assumption that nerve power has in it an 

 electric element, he endeavored to ascertain its source, and 

 finally thinks it is to be found in the sulphur and phosphor- 



