BULLETIN OF THE UNITED STATES FISH COMMISSION. 433 



' Vol. IV, IVo. 28. Washington, B. C. Sept. 29, 1 884. 



210 rVOTE ITPOIV THE EFFECT OF HlCSn PBESSBTKES OIV TEIJE T2- 



TA«,ITV OF MIi-^UTE FIIESH-\*'ATEB AI\» SALT-^VATEK OfSOAN- 



By A. CERTES. 



I have the honor of presenting to the Biological Society the note* 

 which I deposited in the Academy at its session of March 17 last, on' 

 the cultnre under shelter of germs from the waters and sediments of 

 the Travaillenr and the Talisman. [Comptes rendus, No. 11, p. C90.)) 

 On this occasion I ask permission to give a brief review of some new 

 experiments which I have made with various microscopic organisms hj 

 subjecting them to high pressure for a period varying from seven hours 

 to seven full days. This communication will, I hope, tend to lessen, if 

 not to cause to disappear entirely, the differences, more apparent than- 

 real, which Dr. Regnard pointed out at the last session between the- 

 conclusions reached by his experiments and by mine. Thus I fully 

 agree with Dr. Regnard's opinion " that the infusoria of the surface of 

 the sea could not, without slow acclimatization, live in the depths, and! 

 that for these parts, as for all the others, there must be an abyssal 

 fauna." It is nevertheless true that our experiments differ, both as to. 

 the aim we have in view and the conditions under which they have' 

 been made. 



As far as I am concerned I have made it my aim to find out by whatr 

 processes organic matter has been reduced to an inorganic state in the- 

 great depths of the sea. After the expedition of the Travailleur, in, 

 1881, I at first searched directly for " microbes " by examining micro- 

 scopically the sediments ob^tained by osmic acid and treated with color^ 

 ing reagents. JSTot finding anything by this process, I had recourse to. 

 the method of cultivation ; but from the very beginning I was fully 

 aware that it would not be capable of producing genuine '• microbes " 

 from great depths, like those from the material gathered by the Talis- 

 man, but that I would have to place these " microbes " under their 

 normal conditions of physiological activity. It is difficult to produce 

 these conditions, and it is only by way of experiment that I at first 

 sought to ascertain the effect of high pressure on unicellular organ- 

 isms, both infusoria and " microbes," which we find near the surface. 

 1 had also to study how to avoid sudden pressure and a sudden stop- 

 page of pressure, which in nature occur only by way of accidents. 



At my request, and by the kind intercession of Mr. Cailletet, Mr. 

 Ducretet has slightly modified the regulations for using his apparatus. 



* Dc Taction des hautcs prcasiovs siir la vUalU6 des min'o-organismes d'eau douce et dkau 

 de met: Paris, 1884. Translated from the French by PIerman Jacobson. 

 Bull. U. S. F. 0., 84 28 



