iv TEMPERATURE AND LIFE 205 



hand, I think no naturalist, knowing anything about 

 the mutual interaction of living organisms, would 

 dismiss the case entirely, and say that any influence 

 of the one on the other is impossible and incredible. 



Alterations in the forms of animals, especially 

 molluscs, are very frequent, and in some cases a sug- 

 gestion as to the causes may be gained, when the 

 deformed animals live under circumstances where a 

 departure from the normal conditions is obvious. It 

 is well known that many warm springs contain a large 

 number of living plants and animals. Physa acuta, for 

 instance, has been found in waters at 30 Cent (Fischer), 

 and even at 33 and 35 Cent, (at Dax, according to 

 Dubalen, in Soc. Linneenne de Bordeaux, vol. xxix. 

 p. 4), while Turbo thermalis lives at 50 Cent, at 

 Albano, 1 and Neritina thermophila between 50 and 

 60 Cent, in New Brittany Island, according to Studer, 

 etc. But it would seem that when individuals which 

 have not been gradually accustomed to such con- 

 ditions, through their ancestors, live for the first time 

 in such unnatural media, many deformations are apt 

 to appear. M. G. Regelsperger 2 has observed the 

 following case. The waters of an artesian well, sunk 



1 De Blainville's article Mollusques, in the Dictionnaire des Sciences 

 Naturelles, 1816-30. 



2 Deformations remarquables de Physa acuta observees a Rochefort 

 surMer. Actes de la Societe Linneenne de Bordeattx, vol. xxxix. (vol. ix. 

 of 4th series), 1885, p. 117. 



