SOCIETY OF PHYSICS AND NATURAL HISTORY, OF GENEVA. 353 



tliat the chloroform acts in this experiment simply as an auffisthetic, 

 and not as a caustic, which destroyed the brain, leaving- the frog in the 

 state of a headless animal. From these experiments M. Prevost has 

 come to the conclusion that chloroform anossthetizes in the nervous cen- 

 ter only the parts vrith which it is directly in contact, and that it does 

 not act at a distance, as M. Bernard believed. 



M. Brown-Sequard has produced some phenomena of epilepsy upon 

 Guinea pigs by means of hemisections of the marrow or of the 

 section of a sciatic nerve. Dr. Prevost has obtained the same 

 phenomena by the amputation of a thigh of one of these animals. In 

 order to provoke a nervous attack it is sufficient to excite the zone 

 called epileptic, which comprises the half of the surface corresponding 

 to the member amputated, and immediately the animal is thrown into 

 convulsions. The excitability of this zone decreases, however, with the 

 continuation of the experiment, and it is always more difficult to pro- 

 voke a new crisis. The study of this artificial epilepsy will, without 

 doubt, throw some light upon the kind and nature of natural epilepsy. 



MEDICINE. 



Dr. Lombard has been investigating for several years the climate 

 of mountains, a subject which more than any other ought to interest 

 the physicians of Switzerland. His later researches are directed to the 

 effect which these climates exercise upon pulmonary phthisis, a question 

 which he had been appointed to investigate by the commission estab- 

 lished at Samaden, for the purpose of its elucidation. He estimated 

 that a residence in high altitudes would prevent the development of 

 the phthisis, and even cure it, either in developing the pulmonary em- 

 physema, or by favoring the functional periphery activity. (The work 

 of M. Lombard has appeared in the Medical Bulletin of Switzerland.) 



Finally, M. Alphonse de Candolle read a notice which likewise de- 

 serves to be registered in the medical rubric. It is, in fact, an appli- 

 cation to this science of the Darwinian principles deduced from natural 

 history, inasmuch as it treats of an effect of selections rendering variable 

 the intensity of maladies when they are very deadly. According to the 

 author, when a disease has severely attacked that portion of the popula- 

 tion not advanced in years, the following generation, descending from 

 persons not disposed to take this disease, Avill also be in the same 

 condition by an ordinary effect of the hereditary law. There is, there- 

 fore, a reason for the diminution of the epidemic. We can likewise 

 explain why its attacks are most severe the first time it appears among 

 a population, and why it afterward becomes rare or less fatal, which 

 has been the case with most of the diseases of this kind. At the end 

 of several generations, however, a population moderately attacked by 

 a disease resembles the condition of a population who have never had 

 it, and the result is a double intensity. Applying these principles to 

 the small-pox, M. de Candolle estimated that at the time when Jenner 

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