1016 The American Naturalist. [November, 
lines. Dr. Forsyth Major appears to have overlooked this aspect of 
the case, and it will be necessary to dispose of this theory before pro- 
gress in any other direction can be made.—E. D. Cope. 
Effects of Temperature on the Coloring of Lepidoptera. 
—In Insect Life, Vol. III, p. 481, is given the following resumé of a 
series of temperature experiments conducted by Mr. Merrifield in 
pedigree moth-breeding, begun in previous years, on the pupa of 
Selenia illustraria and Ennomos autumnaria, 
By careful and long continued experiments Mr. Merrifield has 
demonstrated the possibility of producing artificially from a single 
brood of a moth, subject to seasonal dimorphism, four distinct “ tem- 
perature” varieties, viz.: summer markings with summer coloring, 
summer markings with an approach to spring coloring, spring mark- 
ings with summer coloring, and spring markings with spring coloring. 
The conclusions reached as a result of this series of experiments are 
that the coloring and markings of the moth are affected by the tem- 
perature to which the pupa is exposed, the marking being chiefly 
produced by long continued exposure; that the coloring is affected 
chiefly during the stage before the coloring of the perfect insect begins 
to show; that a low temperature during this stage causes darkening, 
a high temperature producing the opposite effect, a difference between 
80? and 57? being sufficient to produce the extreme variation in dark- 
ness caused by temperature; a further lowering of temperature having 
no further effect ; that nearly the full effect in coloring may be pro- 
duced by a range of temperature of from 76? or 80? to 65? in autum- 
naria, and from 73? to 60° in illustraria ; that dryness or moisture 
during the entire pupal period has no appreciable effect on the coloring 
of the adult. 
A general conclusion which the author ventures to suggest—pro- 
vided we accept the theory of Professor Weismann, that existing forms 
of North American and European Lepidoptera have come down from 
a glacial period—is, that “icing” the pupa causes the insect to revert 
to its earlier form, and that experiments of the nature here recorded 
might be of material assistance in tracing the evolution of the mark- 
ings on the wings of the most highly developed forms. 
In a supplementary note Mr. Merrifield adds that it is possible to 
cause either the summer or winter form to take on the coloring of the 
other, and produce from moths from the summer pupa, specimens that. 
resemble those from the winter pupa, but not vice versa. 
The details of these experiments can be found in Part I, Trans. Ent. 
Soc., London, 1891, pp. 155-167. 
