(rks) 
metrid moths of the genera Selenia and Hnnomos, certain 
species of which have normally two differing seasonal forms 
in England, and they extended to the application of both 
icing and forcing for various periods in all stages from egg 
to imago. The results were of much interest from many 
points of view, and more especially as showing (a) that the 
continued application of low temperature to the pupz reared 
from eggs laid by the spring brood produced moths more and 
more like their parents, instead of the natural summer form ; 
(5) that the opposite experiment of applying heat to the pup 
from eggs of the summer brood was fatal to a majority of 
individuals, and produced in the survivors a proportion of 
the summer form but mainly specimens intermediate only 
between the spring and summer types ; (c) that it was in the 
pupal state that temperatures exercised their chief influence ; 
(d) that forcing produced pale and comparatively spotless 
moths, while cooling or icing produced dark and much 
spotted ones. Another noteworthy point was that the ap- 
plication of moisture in combination with various tempera- 
tures to the pupe of S. tetralunaria and L. autumnaria had 
no effect on the resulting moths. 
The dimorphic species next treated by Mr. Merrifield in 
1892-93 were Pieris napi, Araschnia levana, and Chryso- 
phanus phleas. The results in the first and second of these 
species were generally confirmatory of those obtained by 
previous experimenters. In the case of C. phleas, which, 
though many-brooded almost throughout its immense range, 
does not exhibit seasonal dimorphism in Europe except in 
Southern Italy, Corsica, and Greece, forcing caused on the 
upperside the dusky suffusion and larger black spots of the 
forewings characteristic of the southern summer form eeus, 
while cold induced exactly the opposite characters in the fore- 
wings and also a great broadening and radiation of the 
coppery band in the hindwings. In 1896, Mr. Merrifield 
experimented on pup of Pieris daplidice, and found that 
forcing produced the ordinary summer form, while cooling for 
six weeks brought out the spring form bellidice. 
I have here only very briefly mentioned those of Mr. 
Merrifield’s experiments which dealt with seasonally-dimorphic 
