222 THE AMERICAN MONTHLY [Au 



forms were produced which had all the characters of a 

 supposed distinct species, Artemia muehlaiLsenii. The re- 

 verse experiment was then tried. A small quantity of the 

 water was gradually diluted, and though conducted for 

 only a few weeks, a chang^e in the direction of Artemia 

 salina was very apparent. 



"Led by these experiments he tried still others: Taking 

 Artemia salina, which lives in brine of moderate strength, 

 he gradually dilluted the water, and obtained as a result 

 a form which is known as Branchinecta shaefferi, the last 

 segment of the abdomen having become divided into two. 

 Nor is this change produced by artificial means alone. 

 The salt pools near Odessa, after a number of years of 

 continued washing, became converted into fresh water 

 pools, and with the gradual change in character, Artemia 

 salina produces first a species known aa Branchinecta 

 spinosus, and at a still lower density Branchinecta ferox, 

 and another species described as Bra7ichinecta medi^is.'' 



Observations on the artemisB of the Salt Lake under con- 

 ditions of slow increase or decrease of the brine density 

 indicate the occurrence of changes in structure, but no 

 long continued experiments of conclusive results have 

 been reported. 



The artemia is intereBting to the zoologist as furnish- 

 ing an example of parthenogenesis, i. e., reproduction by 

 means of unfertilized egga. Hiebold of Munich has inves- 

 tigated this subject, and he announces that with the en- 

 tomostracans, Apus and Artemia, tlii« parthenogenic re- 

 production is common. He reared several broods com- 

 posed entirely of females ; yet from these, eggs were pro- 

 duced which hatched vigorous young. Packard treats 

 parthenogenesis as a modified process of reproduction by 

 budding. 



The egg» of the artemia are capable of sustaining long 

 continued drought without losing their vitality. Eggs 

 have been sent in mud from the Salt Lake to Munich, 



