TH 
AMERICAN NATURALIST. 
Vol. VII.—SEPTEMBER, 1873.—No. 9. 
ece DTD I> 
“CONTROLLING SEX IN BUTTERFLIES.” 
BY CHAS. V. RILEY, M.A. 
Tae article with the above title by Mrs. Mary Treat, in the 
March number of the NATURALIST, has attracted a good deal of 
attention, and most naturalists will be proud that a lady has set 
the example of making such investigations. But while I fully con- 
cur with the authoress in the deduction that the female in insects 
and especially in Lepidoptera, ‘requires more nourishment than 
the male,” I cannot follow her in the other conclusion “that sex 
1S not determined in the egg of insects.” Were this conclusion 
Well founded it would upset what most physiologists of note be- 
lieve to be a fundamental principle, viz., that, in the individual, 
Sex is determined at the moment of conception, no matter at what 
Stage of growth it becomes ascertainable by us. That such is the 
case with the higher animals will scarcely be doubted, and to 
reason from analogy that it is the case with the whole animal 
“ngdom is quite as natural, though equally as unsafe, as it was in 
years gone by to argue that lucina sine concubitu was an impossi- 
bility; or that larval reproduction, in insects, could not possibly 
take place. It is, therefore, worth while to weigh the evidence for 
and against the possibility of controlling sex in larve. 
‘ Mrs. Treat, whom I know to be a good observer, and whom I 
esteem as a correspondent, had already, in 1871, communicated 
to me her belief that she could control the sex in butterfly larvæ, 
Semis tate Oat of cheese of Gane at Wastinglons ATOPY ACAPEOT OF 
AMER. NATURALIST, VOL. VII. 33 (518) 
