196 THE CANADIAN ENTOMOLOGIST. 



in a similar manner as the European ones. The two European species 

 of Artemia are remarkably different. Artemia salina has a strongly bifid 

 tail surrounded by 15 to 20 bristles and narrow gills ; Artemia mulhauseni 

 has a rounded tail without bristles, and very large gills. This latter 

 species lives in pools of a very concentrated salt water of 25°Beaume; the 

 other species in common salt water of about 8°. In 1871 a dam which sur- 

 rounded a salt pool containing Artemia mulhauseni, broke down by accident 

 and the sea water washed in at the same time ; Artemia salina, which 

 abounds in the sea water, appeared in large numbers in the pool. The 

 dam was immediately repaired, and in the space of three. years the amount 

 of the salt in the pool arrived gradually at the same concentration as 

 before. 



A Russian naturalist, Mr. Schmaukevitch, living near the spot and 

 studying carefully Artemia, was astonished to find the species somewhat 

 changed in every following generation, till in three years the Artemia 

 salina was changed entirely into mulhauseni. The fact was so extraordinary 

 that he decided to confirm it by a more conclusive proof. He raised 

 at home in open glass dishes Artemia salina, and by successive additions 

 of salt to the water, he was able to transform the species into Artemia 

 mulhauseni. To make the counter proof he diluted the water gradually 

 and the species returned to the form of Artemia salina. But by con- 

 tinued dilution of the water he was more surprised to find that in the 

 third generations the long abdominal segment began to be separated into 

 two segments, and finally to be changed as in a Branchipus. He found 

 later in salt pools of only four to five degrees (living together) Artemia 

 salina and Branchipus spinosa, and in water with a lower degree of salt 

 two other related species, Branchipus ferox and media. 



Mr. Schmaukevitch has mads similar experiments with similar results 

 on Daphnia, Cyclops and Canthocamptus, which he has not yet published. 

 There can be no doubt about the facts under such conclusive proof, and 

 Prof. V. Siebold is now engaged in raising the American spe^'^s from 

 Salt Lake for similar experiments. These facts oblige us to con _1 1 



these different forms as belonging to one and the same species, since it is 

 possible to change at will one form into another by altering the conditions 

 of living. As long as this is possible they cannot be considered as differ- 

 entiating or Darwinian species. We have now the proof that specific 

 characters exist which do not depend on minuter points of structure. 

 Therefore we are taught that we must considerably enlarge the char- 

 acters of species and those of the genus. 



