30 Experimental Zoology 
name implies) and on the leaves of certain shrubs. It is now 
found on a number of other trees. 
Certain aberrations have been traced directly to the food of 
the caterpillar. The caterpillars of Ellopia prosapiaria living 
on the pine become reddish butterflies; but if they occur on 
the fir, they give rise to the aberration prasinaria, which is 
green. An analogous case is that of Cidaria variata, whose 
caterpillars living on the fir give rise to a form that is gray, but 
on the pine produce a variety obeliscata, which is brownish red. 
In certain countries where a variety almost entirely replaces 
the parent species it is not uncommon to find the caterpillar on 
a different plant. For example, Lasiocampa quercus lives on 
different food plants in different countries. In Scotland, where 
the variety callunze dominates, the caterpillars live on the 
heather; in the South, where the variety roboris is found, the 
caterpillars live on the oak, Quercus robur. 
In changing the food, Pictet often made use of plants that 
were very different from the natural one. Thus the oak was 
often replaced by the esparcette, by the dandelion, by the 
lettuce or by the pimprenelle.? In other cases it was replaced 
by the walnut, neflier,? and the sorbier.* In some cases a food 
plant closely related to the normal was the only one that could 
be substituted; thus the European Evonymus europeus (spindle 
tree) can be replaced by E. japonicus. Certain species refuse 
all food but their natural one. Other species can be induced 
to take a different nourishment, but only after much persever- 
ance. Others, such as Lasiocampa quercus, when young ac- 
commodate themselves to nearly all kinds of vegetation, but 
once full size, many plants are rejected. The acceptation of a 
new kind of food is transmitted by heredity, and individuals 
whose parents have become accustomed to a strange food will 
consume the same food with greater facility. Some of the 
effects that Pictet obtained by changes in the food are as fol- 
lows : — 
? Onobrychis sativa, or holy clover. 5 Mespilus germanica, or mespit. 
? Poterium sanguisorba, or salad burnet. 4 Sorbus ancuparia. 
