232 GENEVA SOCIETY OF PHYSICS AND NATURAL HISTORY. 



and, one belonging to the genus Brissus, the other, the EcJmiolampas 

 Alexandri. This genus made its appearance with the Tertiary forma- 

 tion. The species, numerous in the Eocene, less extensive in the Mio- 

 cene, rarer still in the Pliocene, number four at the present time. (See 

 vol. XXIV of our Memoirs.) 



A few years hence the conchologists of our country would be much 

 puzzled to explain the appearance of two fresh water shells, Paludina 

 vivipara and Planorbis corneus, if M. H. Fol had not taken the precau- 

 tion to inform our society that he had put in the salt marsh of Sionnet a 

 certain number of these mollusks to see whether they could be accli- 

 mated. 



4. Animal physiology and medicine. — Professor Schifif has sought to 

 modify the hypothesis of M. Dubois Eaymond, of the electric nature 

 of the nervous agent, and to determine whether electric currents are 

 produced in the nerves of living animals. Using very sensitive appa- 

 ratus and operating upon the sensitive nerve of a frog decapitated 

 just at the moment of the experiment, the result was negative. In 

 other experiments M. Schifif employed the muscles of the thigh of a 

 frog cleaned and arranged so as to serve as a connection between 

 two electrodes. He observed no current, and the learned professor 

 concluded that none was produced, in the absence of all lesion in 

 the uncut nerves. He, however, immediately perceived, the formation 

 of a current when the nerve was merely pinched. After the hypoglos- 

 sal nerve of a dog has been cut and the wound healed, the nerve is no 

 longer in a normal condition. Uncovered at the moment of experiment 

 it gives variable electric efi'ects. In operating upon the pneumogastric 

 nerve of cats and rats under the influence of alcohol and curara, kept 

 at the temperature of the surrounding air, M. Schifif observed no cur- 

 rent; but, on binding or tying the nerve, the curreut was formed imme- 

 diately. M. Schifif thinks, therefore, that in the normal condition of 

 the nerve and in the state of immobility of the living animal there is no 

 curicnt ; that when the current is produced, it results from the death of 

 the nerve, or from nervous activity and the contraction which accom- 

 panies it. 



The same learned gentleman addressed the society upon the proper- 

 ties of nicotine as a poison, and the action of the liver under the effects 

 of this poison. The nicotine injected under the skin of a dog produced 

 death in a few moments. When the nicotine was forced through the 

 liver, its effects were weakened; the nicotine is destroyed by this or- 

 gan. The nicotine doubled has very nearly biliary activity. Until 

 now only iocyamine was known which produced similar effects; and 

 according to M. Lautenbach the action of the liver is more complete 

 upon this poison than upon the nicotine. One-sixtieth of a drop of this 

 substance is sufficient to kill a frog, after the liver has been tied, al- 

 though one-twentieth is sufificieut in the ordinary state. The tying of 

 the vena porta of a dog, of a cat, or of a rabbit, produces the death of 



