386 BIOLOGY AND ITS MAKERS 
reduced in their development, rather than increased; bu 
manifestly the short-winged race of beetles is better adaptec 
to live under the particular conditions that surround thei 
life in these islands. 
While this is not a case of increase in the particular organ 
it illustrates a progressive series of steps whereby the organ 
ism becomes better adapted to its surroundings. A simila 
instance is found in the suppression of certain sets of organs 
in internal parasites. For illustration, the tapeworm lose: 
particular organs of digestion for which it does not hav 
continued use; but the reproductive organs, upon which the 
continuance of its life depends, are greatly increased. Suck 
cases as the formation of short-winged beetles show us that 
the action of natural selection is not always to preserve what 
we should call the best, but simply to preserve the fittest. 
Development, therefore, under the guidance of natural selec- 
tion is not always progressive. Selection by nature does 
not mean the formation and preservation of the ideally per- 
fect, but merely the survival of those best fitted to their 
environment. 
Color.—-The various ways in which natural selection acts 
are exceedingly diversified. The colors of animals may be 
a factor in their preservation, as the stripes on the zebra 
tending to make it inconspicuous in its surroundings. The 
stripes upon the sides of tigers simulate the shadows cast by 
the jungle grass in which the animals live, and serves to con- 
ceal them from their prey as well as from enemies. Those 
animals that assume a white color in winter become thereby 
less conspicuous, and they are protected by their coloration. 
As further illustrating color as a factor in the preserva. 
tion of animals, we may cite a story originally told by 
Professor E. S. Morse. When he was collecting shells on the 
white sand of the Japanese coast, he noticed numerous white 
tiger-beetles, which could scarcely be seen against the white 
