238 STUDIES IN GENERAL PHYSIOLOGY 



tiou of the water slowly rose to 25 Beaum6, after which the salt 

 again began to be precipitated. 1 



In the course of this time progressive changes occurred in 

 Arteniia salinn, so that the Artemia present in the year 1874 

 had the characteristics of the species A. mulliausenii. These 

 changes in detail are the following: (1) The adult animals 

 of A. mulhausenii are not so large as the adult animals of 

 A. salina. (2) Artemia salina has caudal bristles and caudal 

 appendages, which are lacking in Artemia uiulhausenii ; as 

 the coneeiitration of the salt water increased, the caudal 

 bristles became progressively smaller. (3) The surface of 

 the gills is longer and narrower in Artemia salina than in 

 Artemia mulhausenii. Ludwig (in Leunis's $////o/W.s) gives 

 only the tirst two points. According to this author, the 

 length of A. mulhausenii is 08 mm. ; that of Artemia salina, 

 8-10 mm. Schmankewitsch was able to convert A. salina 

 into A. miilhausenii by increasing the amount of salt in the 

 aquarium. 



2. By growing Artemia in salt water that was gradually 

 diluted, Schmankewitsch obtained a variety having the 

 characteristics of the genus Branchipus Schaeff. The differ- 

 ences are very slight. Artemia has eight, Branchipus nine, 

 footless terminal segments; and, what is of importance to us, 

 Branchipus ferox attains a greater length, the less concen- 

 trated the salt water in which it lives. 



3. If we do not allow ourselves to be influenced by the 

 nomenclature of the systeniatist, the experiments and obser- 

 vations of Schmankewitsch show ihat the effect of the con- 

 centration of the s<tlt shows itself most distinctly in the. 

 longitudinal growth of the entire animal and of some of its 

 organs; ami tin's always in such a way that iritk an increase 

 in the concentration of the solution the longitudinal groir/// 



1 Beaume's hydrometer is graduated, according to Wullner, so that the point to 

 which it sinks in water is marked 0; that, to which it sinks in a solution of flftf-cn 

 p.irts of so limn chloride and 85 parts of water, 15. Water of 8" Boaum6 therefore 

 contains about 9 per cent, salt; that of ii" Beaume, about 23 per cent. 



