ORGANIZATION AND GRowWTH 239 
of the entire animal or the individual organs is decreased. 
The result is therefore similar to that obtained in the pre- 
vious experiments; wherefore I believe that the influence of 
concentration upon the conversion of the genera Artemia 
into Branchipus is to a large extent nothing but an expression 
of the dependence of animal growth upon the absorption of 
water. Schmankewitsch also mentions that in the same 
length of time the animals in the dilute salt solution 
(Branchipus) grow more rapidly than those in the concen- 
trated salt solution (Artemia): ‘““At the same temperature, 
the growth of specimens of Artemia salina in highly concen- 
trated sea water is less than a third as great as the growth 
of Branchipus ferox in the less concentrated sea water.’” But 
that we are, indeed, justified in this case in substituting for 
the conceptions of “adaptation” and “change of species” 
—toward which Schmankewitsch takes a more critical view 
than most Darwinians—the osmotic dependence of longitu- 
dinal growth upon the concentration of the salt solution, is 
well shown by a fact, which is especially emphasized by 
Schmankewitsch, that the ‘‘change” persists in the suc- 
ceeding generations only as long as the animals remain in 
the sea-water of the altered concentration—as should be the 
case if we are dealing merely with osmotic effects during the 
period of growth. Since not only the absorption of water, 
but also the secretion of water, must be considered in such 
experiments as have been detailed here, it is to be expected 
that the growth of all animals and all organs is not affected 
to the same extent by changes in the concentration of the 
salt solution. 
4. Schmankewitsch interprets the effect of the concentra- 
tion of the salt solution upon changes in the characteristics 
of the animals in a different way; he attributes it solely to 
the fact that with the increase in the concentration the 
amount of air dissolved in the salt solution is decreased, and 
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