GENERAL NOTES. 
405 
the winter form is the same as the German summer form ; the German 
winter form does not occur in Italy ; and the Italian summer form (P. 
allous) is not found in Germany. Season-dimorphism is simply the 
splitting of one species into two climatic varieties in the same locality. 
The eggs and larvae never differ. After discussing Heterogeny and 
Metagenesis in the lower animals, the author sums up his conclusions as 
follows : — 
(1.) The differences between species may have arisen chiefly from the 
direct influence of external conditions of life. (He thinks Darwin is 
mistaken in attributing the colours of Lepidoptera entirely to sexual 
selection.) 
(2.) Every alternation of climate during geological epochs must have 
given rise to a fresh series of species of Lepidoptera. 
(3.) All the individuals of one species are modified in the same 
direction by climatic influences, which is due to the physical constitution 
of each species. 
(4.) Periodical causes of variation lead to periodically recurring varia- 
tions, and the series of monomorphic generations becomes a cycle of 
dimorphic or polymorphic generations. 
(5.) Finally, a species can only become variable from the influence of 
altered external conditions of life, more especially when this variation 
takes a definite direction, which again depends on the physical nature of 
the varying organism, which differs in different species, and even in the 
two sexes of one and the same species. 
The work concludes with a detailed account of the author’s experi- 
ments in breeding the different forms of Vanessa levana and Pieris 
rapcB and napi. 
An abstract of the above' work, with an account of some further ex- 
periments on Papilio ajax, is given by W. H. Edwards, Canad. Ent. vii. 
pp. 228-240. 
Prothoracic glands in Lepidopterous larvse ; S. H. Scudder, Psyche, i. 
p. 64. 
On varying the food of larvae, and its effects on the imago ; L. Glaser, 
Zool. Gart. xvi. pp, 263-266. 
A summary of observations on digestion in the larvae of Cossus Ugni- 
perda and Liparis dispar, and in the images of Papilio machaon, Vanessa 
io, polychloros, and urticce is given by F. Plateau, Mem. Ac. Belg. . xli. 
No. 2, pp. 80-97. 
On the preparation of larvae for collections ; G. J. Wittmack, Abh. 
Verb. Hamb. 1871-74, pp. 75-90; 
Varieties, &c., of Lepidoptera \ G. B. Corbin, Ent. viii. pp. 268 & 269. 
Hybernation of Lepidoptera ; T. Goossens, Bull. Soc. Ent. Fr. (5) v. 
pp. xxiv. & XXV. 
A discussion on variation in Lepidoptera ; CR. Ent. Belg. xviii. pp. 
xxiv. & XXV. 
On the fertilization of the flowers of Hesperis tristis by various Lepi- 
doptera, and of Lilium martagon by Macroglossa stellatarum, H. Muller, 
Nature, xii. pp. 60, 51, 190 & 191. 
