238 STUDIES IN GENERAL PHYSIOLOGY 
tion of the water slowly rose to 25° Beaumé, after which the salt 
again began to be precipitated. 
In the course of this time progressive changes occurred in 
Artemia salina, so that the Artemia present in the year 1874 
had the characteristics of the species A. miilhausenii. These 
changes in detail are the following: (1) The adult animals 
of A. milhausenii 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 miilhausenii; as 
the concentration 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 milhausenii. Ludwig (in Leunis’s Synopsis) gives 
only the first two points. According to this author, the 
length of A. milhausenii is 6-8 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 systematist, the experiments and obser- 
vations of Schmankewitsch show that the effect of the con- 
centration of the salt shows itself most distinctly in the 
longitudinal growth of the entire animal and of some of tts 
organs; and this always in such a way that with an increase 
in the concentration of the solution the longitudinal growth 
1Beaumé’s hydrometer is graduated, according to Willner, so that the point to 
which it sinks in water is marked 0; that to which it sinks in a solution of fifteen 
parts of sodium chloride and 85 parts of water, 15. Water of 8° Beaumé therefore 
contains about 9 per cent. salt; that of 25° Beaumé, about 2) per cent. 
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