Action of the tenpcraturo* — - The larvae, taken from vmter at 

 17 degrees, 'lied in a fexr i.iinutes ot a tenpernture above 30 

 de^.;rees» They resisted for a lon;^er tine betvreen 30 and 26 

 de^;rees, but ended by dying* They live indefinitely in sea 

 water belcviT 24,5 to 25 degrees. 



Action of salinity s — - In the brackish v;aters, the larvae coning 

 from v;ater "at 1025 do not appear troubled until the density 1020o 

 They die rapidly at densities lovrer. than 1015. The liioit of 

 dilution that they are able to stand is in the neighborhood of 

 1017.5 

 ;"■»-•■ 



.-..•■ In super saline waters' the larvae stand a density of 1033, 

 At 1042, they become immobile, but the same, after 20 mdnutes of 

 immersion, res\jme their activities v/hen one reiJlaces them in 

 normal v:atero At 1051, almost all die in less than 20 iiinutes; 

 at 1060,- all die in a few instants. 



Action of pH . — - The larvae tolerate very well water brought to 

 pH 2 by prolonged paddling with air deprived of CO"^; they bear 

 equally -■.-•ell waters acidified by CO to pH 6o4; about this point 

 only they shcvr temfiorary troubles: fall to bottom, immobilized, 

 from, which they recover completely afterwards. At pH 6,2, they 

 die in ten minutes; at pK 5,6 in four minutes j at pH" 5,2 in one 

 minute. 



These experiments show that -Qie lobster larvae, a little time 

 after hatching, are sensitive to elevations of temperature and to 

 decreases-, of salinity, insensitive to variations of pH which they 

 may. encounter in the i.iarine environments where they develop. 



The limits that we have deterrdned appear to us to agree re- 

 markably wit h-- the geographic extension '^f the si^ecies. One knovra 

 that the european lobster is found the length of the east coast 

 of the Atlantic, froi.i I'lorvmy to the iJediterranean, It extends to 

 the north Tronsoe at 69 or 70 degrees north latitude but it is 

 very rare, if not un]:n^wn at Iceland, One finds it in the Worth 

 Sea but it does not penetrate "into the Baltic. It becomes less 

 frequent in the Mediterranean vjhere it disapp.oars from the Adriatic 

 and from Tunis, The american species, very akin, is loiovm from 

 Labrador to Virginia v;hore the surface water reaches just, in sumraer 

 at the time of spavming, a m.aximun temper at-ure of 24,4 degrees. It 

 seems therefore that the geographic distribution of the larvae is 

 lir.iited in "the north by temperatures too 1o\t 'for the normal develop- 

 i-Tent of the larvae; to the south, by a mxiximum temperature of 24 or 

 25 d.egrees on the surface near the coasts; in the interi'ir seas, 

 by the brackishness, whenever the density is lowered below 1020 

 or 1017. 



117 



