iv TRANSFORMATIONS OF ARTEMIA 105 



Herr Schmankewitsch l observed that the transformation 

 into A. Milhausenii, M. Edw., in a lake in South Eussia, in 

 consequence of the increase of saltness, was completed after 

 an interval of three years. The latter animal differs from 

 A. salina chiefly by the absence of the caudal lobes. 

 Schmankewitsch has also produced the A. Milhausenii 

 through artificial cultivation, i.e. by rearing several genera- 

 tions of A. salina in water of increasing saltness. 



The species of Branchipus into which Artemia salina is 

 transformed in consequence of the dilution of the salt water 

 in which it lives is Branchipus spinosus Grb. We have 

 here, therefore, a transformation not into a form which is 

 described merely as a distinct species, but into one which is 

 ascribed to another genus. 



Branchipus has more somites than Artemia. It must be 

 regarded, compared with Artemia, as . the phylogenetically 

 older form, and thus the transformation from Artemia into 

 Branchipus can be considered as a reversion. But not so the 

 transformation from Artemia salina into A. Milhausenii, for 

 the latter stands higher in evolution than the former. 

 Moreover, it is most remarkable that the saltness of the 

 water has also an effect on the duration of the development : 

 a higher proportion of salt retards, a lower accelerates it. 



In other Crustacea also, in minute Daphnire, Schmankewitsch 

 observed similar changes as a consequence of the increase or 

 decrease of saltness. In my opinion, there can be no doubt 

 that, among other cases, the nature of the waters in which 

 they live has governed the evolution of new forms among 

 our fresh -water fishes. The species of Salmo in our fresh 

 waters, which are so nearly related to one another, are 

 evidently in part local forms, or they are obviously influ- 

 enced by the character of the water in which they live. 

 Especially noteworthy in this connection is the lake trout, 



1 Zeitsch. f. vriss. Zoologie, Bd. xxv. Suppl. and xxix. 



