The Making of Species 
normal colouring. Schmankewitsch made the 
discovery that, in the case of the crustacean 
Artemia, he could produce either of two species 
according to the amount of salt in the water in 
which these creatures were placed. He declared 
that the anatomical differences between the 
species Artemia salina and Artemia milhauseni 
depended solely on the percentage of the salt in 
the surrounding water. He further stated that 
by adding still more salt he could change the 
Artemia into a new genus—Lranchipus. More 
recent observers have cast doubt upon these 
results of Schmankewitsch. They, however, 
admit that the degree of salinity of the water has 
some effect on the form of the Artemza, although 
they suggest that factors other than concentration 
affect the result. In any case, it is now well- 
known that changes in the environment effect 
changes in the colouring of many crustacea. 
Pictet has shown that the alternating wet and 
dry seasons in some tropical countries are the 
cause of, or stimulus that induces, seasonal 
dimorphism in some butterflies. He was able to 
effect changes in the colouring of certain species 
by means of humidity. 
The most important cases, from our point of 
view, are those in which the application of 
heat or cold to a pupa has affected the colour, 
shape, etc., of the emerging butterfly. Here we 
have but one factor, that of temperature. All 
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