618 The American Naturalist. [July, 
ZOOLOGY. 
Temperature and Color in Lepidoptera.—At the meeting, 
March 24, 1892, of the South London Entomological and Natural 
History Society, Mr. F. Merrifield exhibited examples of Selenia illus- 
traria, S. illunaria, S. lunaria, Vanessa urtice, Platypteryx falcataria, 
Chelonia caia, Bombyx quercus and var. callune, to illustrate the 
effects of temperature on these species. He prefaced his remarks by 
referring to the experiments of Weismann and Edwards which were 
made on seasonally dimorphic species, and said that his results were 
consistent with those of these gentlemefi; but he went further than 
they did, and he found that by subjecting the pups to certain temper- 
atures he invariably, in the majority of specimens, obtained certain 
results, a lower temperature generally producing darker and more 
intense colors than higher temperatures. In illustraria, a brood 
divided into two portions, and one placed at a temperature of about 
80°, produced normal specimens, while the other portion, placed at 
50° or 60° were strikingly darker in color. The same results, but in 
less degree, were obtained with other forms. In V. urticæ some of the 
examples closely approached var. polaris, the specimens exposed to the 
lower temperature being generally darker and the blue crescents more 
intense in color. In conclusion Mr. Merrifield said that a temperature 
of 47° seemed to stunt the size and produced a large proportion of 
cripples, and higher temperatures than this seemed more conducive to 
health and vigor. It had been suggested that the results he obtained 
were attributed to the unhealthy conditions to which the pupz were 
exposed, but this was not at all a correct explanation; in the 172 spec- 
mens he exhibited 150 were not cripples. Extreme temperatures pro- 
duced crippling, but moderate temperatures were quite sufficient to 
account for the extreme difference in coloring. Mr. Fenn said he had 
since 1859 paid great attention to the earlier stages of Lepidoptera, 
and he assumed that variation was either natural or artificial. 
Natural variation might again be divided into three nearly equal 
causes: heredity, moisture and natural selection. In artificial selection 
the causes might generally be said to be abnormal or diseased. By 
disease he meant a general weakening of the constitution by unnatural 
influences; the least deviation from natural conditions might produce 
variation. Mr. Fenn had had considerable experience in breeding E. 
autumnaria, one of the species relied on, and in the series he exhibited 
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