( Ixiii_ ) 
viewing (in Sect. I.) his experiments as to effects from treat- 
ment of pup with constant moderately high (+37° to 
+ 39° C.) or moderately low (+4° to +6° C.) temperatures 
in the years from 1885 to the beginning of 1895, the author 
proceeds (in Sect. II.) to give an account of the continuation of 
these “ Warm and Cold” experiments during the succeeding 
period from the middle of 1895 to1897. These additional experi- 
ments were made on no fewer than fifty-six species of European 
Lepidoptera (thirty-six butterflies and twenty moths) and on 
a largely-increased number of specimens:; and their results 
were found to be fully confirmatory of those derived from the 
earlier more restricted experiments, affording various fresh 
instances of the production of more or less marked variation 
in the directions previously indicated, viz.: seasonal forms, 
local forms, aberrations, phylogenetic forms, and forms showing 
assumption of the male colouring by the female. Under the 
respective headings of “ Frost-Experiments” (Sect. III.) and 
“‘ Heat-Experiments” (Sect. IV.) the several results are 
given of employing temperatures under 0° C. (0° to —18° C., 
and exceptionally to — 20° C.), and those above + 40° C. (up 
.to +45°C.); and the attempt is made (Sect. V.) to explain 
from the results of these two sets of experiments the active 
cause of most of the “ Aberrations” occurring in nature. 
Attention is directed to the extremely interesting fact that 
the aberrations resulting from the artificial very high tem- 
peratures agree closely with the aberrations found in nature,* 
while aberrations like those produced by the use of very low 
temperatures are never found in nature ; and the inference 
drawn from this is that the typical aberrations occurring 
naturally among the Nymphalidze are produced by the tem- 
porary influence of a high degree of heat (40° to 45° C.). 
I cannot here do more than just refer to the remaining 
* This is well illustrated by Plate IV accompanying the memoir, 
where figures of Aberrations, (a) captured at large, and (b) forced at very 
high temperature, of the following species, are given side by side, viz. : 
Vanessa polychloros, V. antiopa, V. atalanta, and Pyrameis cardui, 
figures 1, 3, 5, 7 differing very slightly respectively from figures 2, 4, 6, 
and 8. (Plate III figures the Aberrations produced in the same four 
species by ‘‘ Frost-Experiments.’’) 
