PROTECTIVE RESEMBLANCES, AND MIMICRY 905 
withered leaves, these creatures change color, putting on 
a grayish and brownish coat of hair. The ptarmigan of 
the Rocky Mountains (one of the grouse), which lives on 
the snow and rocks of the high peaks, is almost wholly 
white in winter, but in summer when most of the snow is 
melted its plumage is chiefly brown. On the campus at 
Stanford University there is a little pond whose shores are 
covered in some places with bits of bluish rock, in other 
places with bits of reddish rock, and in still other places 
with sand. <A small insect called the toad-bug (Galgulus 
oculatus) lives abundantly on the banks of this pond. 
Specimens collected from the blue rocks are bluish in 
color, those from the red rocks are reddish, and those from 
the sand are sand-cclored. Such changes of color to suit 
the changing surroundings can be quickly made in the case 
of some animals. The chameleons of the tropics, whose 
skin changes color momentarily from green to brown, 
blackish or golden, is an excellent example of this highly 
specialized condition. The same change is shown by a 
small lizard of our Southern States ( Anolius), which from its 
habit is called the Florida 
chameleon. There is a lit- 
tle fish (Oligocottus snyder?) 
which is common in the tide 
pools of the bay of Monterey, 
in California, whose color 
changes quickly to harmo- 
nize with the different colors 
of the rocks it happens to 
rest above. Some of the tree- 
frogs show this variable col- 
oring. A very striking in- TW 1e_chopaldot emalontat it 
stance of variable protective bark on whichit rests. 
resemblance is shown by the ; 
chrysalids of certain butterflies. An eminent English nat- 
uralist collected many caterpillars of a certain species of 
