PACKAKD.] TEANSFORMATION OF ARTEMIA. 499 



do we find males in the degraded generations of A. saluia already bear- 

 ing the characters of Artemia milhausenii, and which live in the most 

 saline water. However, we can plainly notice that in the salt ditches 

 and in very small salt lakes drying up in summer, that the males of Ar- 

 temia appear in immense numbers at a certain time of the year, and at 

 a certain concentration of the salt water, as I observed it at a compara- 

 tively rapid evaporation of the water of the salt-water basins at the 

 time of continued drought. Here we have to give ourselves the sohi- 

 tion of the question about the change of this physiological function in 

 consequence of the distribution of generations of a species in another 

 elemejit, together with a certain variation of other functions, and of the 

 animal organism. Referring to this I mention but one of the sides, to 

 which variety b. of A. salina inclines to the genus Branchipus. 



This varietj" has with the species the other structures in common, with 

 the exception of those less noticable aberrations depending upon the 

 element, i e.,princii3allyfrom the lower concentration of the salt water, 

 together with their own organization. So, for instance, are the gill- 

 sacs in the variety a little smaller, but especially narrower than in tlie 

 species; likewise in. the body more of a gray than a reddish color, and 

 more transparent. This form most closely approaches the variety of 

 Branchipus ferox of our salt ditches, but perhaps it is the radical form 

 of B. ferox and B. spinosus. 



Consequently we have, therefore, here three closely allied forms of 

 Artemia: A. salina, A. salina var, «., and A. salina var. h. The species 

 A. salina must justly be regarded as a double form, consisting of ^i. 

 salina and its tirst variety (var. «,), as these two forms iu long past 

 times must have originated by division and formation of races of their 

 generations from one for both middle forms. Eegarding the second 

 variety (var. &.), it represents a form originated from A. salina, and be- 

 came distributed in salt ditches of lesser salt capacity, and it is likely 

 that also a similar offspring of the second variety exists. 



These three forms, however, have so many different characters that 

 they in any case can be recognized as varieties amongst themselves. 

 We find such cases also in other widely-distributed species of Crus- 

 taceans,^ for instance, in Cyclops hicuspidatus Claus, and especially in 

 Cyclops odessanus n. sp., where two [Cyclops hicuspidatus) or still more 

 (C. odessanus) near, but still differing forms under certain external con- 

 ditions, each living in either its peculiar pond in one and the same, or 

 also in different water basins, and where each under certain external 

 conditions or at another season of the year obtains preponderance at 

 least in the number of specimens. But the forms of Artemiaj have the 

 preference before other Crustaceans, inasmuch as the surrounding ele- 

 ment includes less complicated conditions, which by the observer can 

 be kept under better control. 



Among the forms of Artemife we may regard A. milhausenii as one of 

 the most retrogressively developed ones; but as one of the most pro- 

 gressively developed forms we have that which I provisionally call 

 variety h. of A. salina. Parallel to this A. milhausenii lives in very 

 saline water, near the self-deposition of salt, or near the same (about 

 23° to 25° Beaume), but variety h. of A. salina lives in comparatively 

 less saline water (4° B.). 



Our A. salina does not fully agree with that examined by Joly,^ 



1 Consult my paper in the "Schriften." of tlie neorussian Society of Nat. 1875, vol. 

 Ill, 2d part. 

 ^ Joly, Sur 1' Artemia saliua. Annates des Sc. Nat. 1840. 



