(> Isa ©) 
sections of Dr. Standfuss’s treatise ; they include a consideration 
of the mode of action of the frost and heat experiments, a 
discussion as to the nature of aberrations, and an account of 
the further breeding of aberrational Vanessa urtice, and with 
the concluding remarks at pp. 37 and 38 will well repay 
perusal. Some idea of the satisfactory and extensive scale 
upon which the experiments were conducted, may be gathered 
from Standfuss’s statement that he had employed altogether 
during 1895-97 the number of over 42,000 pupz belonging to 
about 60 different species.* 
Weismann’s memoir of 1895, above referred to, contains a 
full record of his later experiments and results in the cases of 
Araschnia levana, Chrysophanus phleas, and Pieris napi, as 
well as in those of Pararge egeria (with its ‘ climatic variety,” 
meione) and Vanessa urtice. It further treats of the effect 
on pup of variously-coloured light, and on hibernating pupz 
of warmth, and concludes with a comprehensive general review 
of the whole subject, including a comparison of the results of 
some of his own experiments with those obtained by Merri- 
field and Standfuss. In the case of A. levana, he not only 
succeeded, by means of temperatures of 27-28° C.,and 30-32" C., 
in obtaining repeatedly a small number of the prorsa-form from 
the second summer generation of that form, but also proved that 
occasionally the same result arose in isolated instances without 
the use of a higher temperature than that of an ordinary warm 
room. It was further established that the intermediate forms 
known as portma, so rare under natural conditions, are pro- 
duced whenever a brood is subjected to an unsuitable tempera- 
ture at the beginning of the pupal stage, occurring indeed 
with the second brood from unusual cold, and with the third 
brood from unusual heat. As regards the seasonal forms of 
Pieris napt it was shown that low temperature effects the 
conversion of the summer form into the winter, only when 
* Dr. E. Fischer, of Ztirich, has also carried out very extensive tem- 
perature experiments on European Lepidoptera with most striking results, 
which are mentioned by Weismann, Merrifield, and Standfuss. I have 
not seen Dr. Fischer’s published accounts of his work, but I believe he 
did not experiment with seasonally dimorphic species. 
