ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 49 



almost amounting to identity. Both results have been repeatedly 

 criticised, the second has been proved inaccurate, and much doubt has 

 arisen in regard to the first. The most thoroughgoing criticism, how- 

 ever, has been that of W. P. Anikin,* published in Kussian, but now 

 made available to the unlearned by a summary by N. von Adelung.f 



Anikin points out that the various species of Artemia which bave 

 been described do not rest on a satisfactory basis (not that they are alone 

 in that), and that some of them are merely cripjde-modirications of A. 

 salina, induced by sudden alterations in the salinity of the water. His 

 experiments showed that if the degree of concentration was slowly and 

 gradually increased, no structural changes of moment ensued. Some 

 slight changes were indeed observed, but they were only " modifica- 

 tions," — not transmissible to the progeny, and disappearing when normal 

 conditions were restored. Moreover, these slightly different individuals 

 were sometimes found together in the same water. 



Unlike previous breeders of Artemia (Joly, Siebold, Vogt, Schman- 

 kewitsch), who only observed parthenogeuetic females, Anikin found 

 males several times in his aquarium, and he associates their appearance 

 theoretically with altered nutritive conditions, in fact with starving. 

 But these males which he reared (probably from unfertilised ova) were 

 remarkable in their behaviour when the salinity was altered ; they 

 retained their characteristic features persistently in contrast to the 

 females who changed. 



It is to be hoped that no one will imagine that the question is closed ; 

 but that we shall bave still more experiments on Artemia ; in the mean 

 time, however, Anikin's four general conclusions will be read with 

 interest. 



The representatives of the genus Artemia show a marked tendency to 

 change, as regards almost all the organs of their body. 



The form-changes depend mainly on the jdiysico-chemical character 

 of the medium. 



The changes in individuals which live in salt-solutions subject to 

 constant dilution with fresh-water do not indicate any transformation 

 of Artemia into Branchipus ; even those in the least salt solutions retain 

 unchanged the characteristics of their genus, especially in the male sex. 



The concentration of the salt solution has certainly an influence on 

 the length of the post-abdomen ; for in dense solutions those with long 

 post-abdomens predominate, in weak solutions those with short post- 

 abdomens. 



Innervation of Vascular System in Higher Crustaceans.^ — Prof. 

 J. Nusbaum has used the intra vitam methylen-blue injection method 

 in his study of the innervation of the vascular system of Palsemon, Squilla, 

 &c. He shows, for instance, on the heart of Palsemon, very large multi- 

 polar much branched ganglion-cells, and the breaking up of the entrant 

 nerve-strands into a very fine network connecting different fibres. Peri- 

 cardium and arteries are likewise very richly innervated. Nusbaum 

 notes inter alia his agreement with Holmgren, that although there are 

 certainly subepidermic multipolar cells connected with nerves (as 



* Mitth. Univ. Tomsk, xiv. (189S) 103 pp. (3 pis.). 



t Zool. Centralbl., vi. (1899) pp. 757-60. 



X Biol. Centralbl., xix. (1899) pp. 700-11 (7 figs.). 



Feb. 21st, 1900 E 



