PHYSICS AND NATURAL HISTORY OF GENEVA. 247 



two lines, to wit: the circumference of the circle determined theo- 

 retically by Prevost and wrongly attributed by authors to Vieth. a 

 circumierence situated in the plane of vision, and of the right line 

 perpendicular to the plane of vision, to which allusion has just been 

 made, and of which M. Alex. Prevost, and later M. Fritz Burkhardt, 

 had already given a theoretical determination. The horopter of 

 Meissner must therefore be entirely rejected. 



It is above all with electricity that animal physiology has relations 

 which become every day more intimate. The Society has been occu- 

 pied on two or three several occasions with questions which connect 

 themselves with this subject. M. Lefevre, of Dijon, has called atten- 

 tion to his experiments on muscular and nervous excitability and 

 irritability after death, which he has succeeded in measuring by 

 determining the intensity of the current necessary to produce excita- 

 tion. In operating on the frog he has found that the irritability of 

 the sciatic nerve goes on at first augmenting for an hour after death, 

 then that it gradually loses its excitability while the muscular con- 

 tractiftility develops itself and attains its maximum at the end of 36 

 hours; four or five hours before the cadaveric rigidity supervenes. 



Professor De la Rive offered, on his part, some considerations on 

 the relations between electricity and the nervous action, while dwell- 

 ing more particularly on the experiments recently published by M. 

 Bernard, which appear to him more favorable to the identity of the 

 two forces than the author seems to believe. M. De la Rive points 

 out especially the analogy which exists between the action of electri- 

 city and the nervous action as to the peculiar state in which one and 

 the other place the nerve, this last not acting as a simple conductor, 

 as some physiologists have supposed, but really in virtue of its electro- 

 molecular constitution, which may be altered by chemical means, such 

 as the vegetable poison known by the name of curare. Recalling the 

 remarkable observations of M. Dubois Reymond, which are altogether 

 favorable to this way of thinking, he judges that it is not necessary 

 to admit in the organic molecules other electric properties than those 

 which belong in general to the molecules of inorganic matter, and 

 that it is sufficient to suppose that every atom, whether it forms part 

 of an organized body or one not organized, is endowed with two 

 opposite electric poles. Only in the first case, namely, that in which 

 there is life, a new force, the vital force, determines, by the particu- 

 lar disposition which it impresses on the particles, an arrangement 

 which permits the manifestation of their electric properties. 



I have mentioned the vital force, and here would'be the occasion of 

 giving an account of the long and interesting discussion to which the 

 simple enunciation of the existence of this force gave rise. There 

 was here a general question connected at the same time with the 

 most difficult points of organic natural history, and with the most deli- 

 cate conceptions of the philosophy of the sciences, namely, those 

 which relate to forces, their nature, their mode of manifestation, and 

 the relations which exist among them. Hence, the physicists and the 

 chemists, as well as the naturalists, took part in this discussion, which 

 we must content ourselves here with merely commemorating, without 



