470 GEOLOGICAL SURVEY OF THE TERRITORIES. 



small number of years, and a comparatively sboi t series of generations, 

 in a salt lake with increased density to transform itself into a form 

 identical with Artemia omtehUiausenii M. Edw., whereby this form is 

 enabled to remain constant, as long as the surroundings are not changed. 



3. Artemia is apt, in artiticiaily domesticating several generations 

 in salt water of gradually decreased density, to progressively develop 

 towards the geinis Branchipus, obtaining thereby its generic characters, 

 nine apodous segments. 



4. In a state of nature salt-water ditches of different density, inhab- 

 ited also by the higher specialized forms of Artemia^ yield the condi- 

 tions for progressive development of Artemia into Brancliipus. 



5. The size of the furcal lobes in Artemia, the number of bristles and 

 their distrdmtiou on the tips and sides of the lobes, are, together with 

 the other generic characters, dependejt on the concentration of the 

 salt water inhabited by Artemia. 



G. At a lower density of the salt water occur also in certain brine 

 ditches Artemioi with ])retty long iurcal lobes, with a considerable num- 

 ber of bristles (up to 22 distributed over each lobe), similar ro Branchipus. 



7. The only characteristic features distinguishing the genus Branclii- 

 pus from the genus Artemia aiv: 



Firstly, the presence of eight apodous postabclominal segments, 

 whereby the last eighth segment is nearly twice as long as the preceding, 

 while in Branchipus there are nine such apodous segments, of winch 

 neighboring segments, by twos, show but a trilling longitudinal differ- 

 ence. 



Secondly, parthenogenesis occurs in Artemia, while in Branchipus it 

 is not yet known to occur. 



8. The last long eighth postabdomiual segment of Artemiw is homol- 

 ogous with the last two i)ostab(lominal segments of Branchipus. 



I have now to a^jpend a few words on the parthenogenetic propaga- 

 tion of our Artemia. 



I had already observed parthenogenesis in Artemia in 1871, while ar- 

 tificially domesticating several isolated generations. It being something 

 new to me at that time, I devoted more attention to investigations on 

 the influence of surroundings on Artemia. relative to mor[)hol()gy. 



Of three isolated generations of $ Artemia salina I obtained, while 

 artificially domesticating them, by parthenogenetic.al propagation, in 

 every density of the salt water that sustained their life, onig females. 

 . . . I mentioned in the "Schriften" of the third meeting of Hus- 

 sian naturalists at Kiew, . . . that the males appear in the lake in 

 great numbers at a moderate density of the salt water. 



For such moderate density I took the density of the Hadschibei 

 Lake in the summer of 1870, it having been literally filled witli Artemiw, 

 Mdience they were thrown on the shores in piles by the waves, where 

 they decayed. 



However, I committed a mistake, overlooking an error iri the ])rotocol 

 of the third meeting at Kiew, having said in my printed report that only 

 at a mean (moderate!) density of the water, siinilar to the density of the 

 preceding year (1870), by domestication as well as during the summer 

 in the lake males appear, instead of having said, only at a moderate 

 density of the water, similar to that of the ]n"eceding year, by domesti- 

 cation as well as during the summer in the lake the males ought to ay- 

 pear. As 1 noticed at the time, that the males of Artemia. appear in the 

 lake at a certain density of the water, I assumed, after I could not ob- 

 tain them either at a higher or lower density, that they still ought to 

 make their appearance at the density for which I took the salt water in the 



