434 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



In the apparatus whicli I use there are two receivers and two manom- 

 eters instead of one. The receivers are either isolated or j^laced in 

 communication, just as it is desired, by means of a stop-cock, which 

 allows to accumulate the pressure or to decrease it, without too many 

 precautions, in the first receiver. One can then, by means of the stop- 

 cock, transmit the effect which has been obtained from one receiver to 

 the other, as slowly as is desired. Thus in all my experiments, except 

 when I made a mistake, it has taken nearly half an hour to rise from 

 to 500 atmospheres, and vice versa. In order to rei)roduce still more 

 completely the conditions of nature, I have endeavored never to exceed 

 from 400 to 500 atmospheres, which represent the average pressure of 

 the depths explored by the submarine expeditions. 



If I have rightly understood Dr. Eegnard's different communications, 

 these conditions, except as regards the experiment of which he has 

 given an account at the last meeting, differ very materially from those 

 which he sought to produce. No wonder, therefore, that the results 

 obtained by me differ from his. 



By working in the manner indicated, and always taking care to de- 

 termine beforehand the species of infusoria or small organisms which I 

 subjected to pressure, I have obtained the following results : 



At a pressure of 100 to 300 atmospheres, maintained for seven, twenty- 

 four, forty-eight and seventy-two hours, certain organisms were killed ; 

 others came out of the apparatus as lively as they entered; others again 

 fell into that state of latent life of which Dr. Eegnard speaks. At 450 to 

 500 atmospheres the number of live organisms decreases, and that of 

 dead organisms, or those which have fallen into a latent life, increases. 

 In the first experiment — of which I have already given an account to the 

 academy — the Chlamydococcus pluviaUs, when subjected for seven hours 

 to a pressure of 100 to 300 atmospheres, all came out of the apparatus 

 as lively as they were when put into it. The majority of the other in- 

 fusoria had died. In a second experiment, prolonged for forty-eight 

 hours, at a pressure of 300 atmospheres, fresh-water infusoria, such as 

 Paramecium colpoda and Vorticelles, had fallen into a state of latent life ; 

 others had died. On the other hand, Eiiplotes charon, Euplotes patella, 

 and Pleuronema marina, marine infusoria, had remained active. Other 

 species, especially Holosticha flava and Actinophrys, had died. 



In the last experiment which I made, fresh-water organisms were for 

 thirty-six hours subjected to a pressure of 520 atmospheres. When 

 taken from the apparatus most of the Chlamydococcus aj^peared to have 

 iallen into a state of latent life ; some had died, and others were still 

 active ; but entirely green individuals had resisted in greater number 

 than those whose chlorophyl had begun to assume a red color. In the 

 same tubes I was able to show to two of your colleagues, a quarter of 

 an hour after they had been taken from the apparatus, rotifers in full 

 activity. The tardigrades, which had fallen into a state of latent life, 

 revived more slowly. In all the experiments certain "microbes," which 



