AND OF LIGHT. 253 



Again, Vire * has obtained somewhat similar results 

 in his observations on the Fauna of subterranean caves 

 and streamlets in France. As regards the Crustacea, 

 he found that Niphargus virei, which is of a rose 

 colour, after a few weeks' exposure to light becomes 

 covered with brown spots, and thus undergoes a rapid 

 return to its ancestral form. On the other hand Gam- 

 marus puteanus, when kept for ten months in the tanks 

 of an underground laboratory, began to lose its gray- 

 green pigment, and after twenty months most speci- 

 mens had entirely lost it. Again, the common Gam- 

 marus fluviatilis, when kept for fifteen months under- 

 ground, developed organs of touch and smell which at- 

 tained nearly half the size of those exhibited by the 

 true cave Niphargus. 



The observations which have been made on Amblyop- 

 sis (a fish found in the caves of the Mississippi Valley) 

 do not agree with the above results. Thus Eigen- 

 mann f states that the pigment is very abundant when 

 the young fish are two months old, but even when these 

 fish are kept in light during growth, they show a de- 

 crease and not any increase of pigmentation, so that a 

 ten-months' fish was found to have taken on the exact 

 pigmentless condition of the adult. Both the pig- 

 mented condition and the subsequent depigmentation 

 are hereditarily transmitted, therefore, and seem prac- 

 tically unaffected by changes of environment acting 

 through a single generation. 



*"La Faune souterraine de France," Paris, 1900; vide Abstract 

 by P. Kropotkin in Nineteenth Century, September, 1901, from 

 which this reference is taken. 



f Biological Lectures, Wood's Holl, 1899, p. 124, 



