iv SCHMANKEWITSCH'S EXPERIMENTS 217 



are bristled, etc." And he again says, " Had I not 

 found all possible transitory forms between salt-ditch 

 and fresh-water specimens, had I not convinced my- 

 self of the variability by domestication of this form, I 

 should have regarded the salt-lake specimen as a new 

 form." 



Other investigations have shown M. Schmankewitsch 

 that Daphnia degenerata is merely a changed and 

 degraded variety of D. magna, while the latter is an 

 intermediate form between the typical D. magna and 

 D. pulex. But among Phyllopods no species seem more 

 sensitive to the influence of the surrounding element 

 than the genera Artemia and Branchipus. Changes 

 in environment are apt to produce such variations in 

 the same generation that two closely allied forms 

 hardly admit of distinction. For instance, Artemia 

 salina, which lives in water whose concentration varies 

 from 5 to 12 of saltness, exhibits at high con- 

 centrations (12 or 15) strong tendencies towards the 

 form of Artemia milhausenii, which is a form able to 

 live in water at 24 or 25, in water where the 

 self-deposition of salt is imminent, and between both 

 forms all transitional types are found, which show that 

 both are really of the same species, since A. milhau- 

 senii may be obtained from A. salina through the 

 increase of the proportion of salt in the water. And we 

 cannot escape the conclusion that either our species 



