324 



ZOOLOGY. 



had gradually become transformed into Artemia milJiau- 

 senii." Sclimankewitscli also made the converse experi- 

 ment with perfect success, for by breeding successive 

 generations in salt water which he made weaker and 

 weaker he brought Artemia milliauseidi back to Artemia 

 salina. Semper adds that it was the constancy of the 

 external conditions of life — the greater or less saltness of 

 water — which in one case determined the character of 

 Artemia milhausniii and in another that of Artemia 

 salina. But the Eussian exjierimenter carried the experi- 

 ment still furtlier: "lie kept Artemia, salina in salt 

 water, which he constantly diluted by adding fresh water, 

 till at last it was perfectly fresh; the crustaceans had 

 meanwhile gone through several generations, and had 

 gradually so completely changed their characters that 

 finally they had acquired those of the genus Branchipus." * 

 Specimens of Linmcea peregra from lakes near the Sea 

 of Aral which are salt for some months and comparatively 

 fresh "for others vary greatly from the normal form. 



A 



B 



Fig. 335. — vl, Limnrp-a peregra fi-om salt marshes near tlip Sea of Aral; B, 

 Lirnnced stitgnalis from mai'shes in llie Aral diytriot which are salt for 

 several months in the year. Xi^. After Cooke. 



The sliells of C<trdhtin editle taken b}^ Bateson from 

 * yemper'a Aniiiiiil LilV', pp. 15G-158. 



