206 Experimental Zoology 
determined, but Crampton found no evidence that the death 
could be assigned to such causes. 
Only 181 perfect moths (97 males, 84 females) emerged; 75 
were imperfect to a slight degree, 38 were malformed, and 16 
failed to metamorphose at all. It will be seen that only 16.6 
per cent of the individuals that pupated became perfect adults. 
Measurements of the pupz show that the survivors are longer, 
narrower, and deeper than the eliminated pupe. It also appears 
that survival does not necessarily or invariably accompany a 
condition of lower variability, although such a relation is gen- 
erally observed. Crampton’s general conclusion is that the 
elimination is based on the general and total efficiency of the 
individual, and ‘‘this is determined by the proper codrdination 
of functional and structural elements. The actual basis for 
elimination is, in a word, ‘correlation.’ If this correlation is 
slight, the individual ranks as unfit; if it is higher, the individual 
is fit and more likely to survive.” Whether the correlation itself 
determines the outcome, as Crampton appears to mean, or 
whether the lack of correlation is due to some deeper-lying im- 
perfection, such, for example, as the presence of disease in the 
caterpillar which determines both the lack of correlation and the 
failure to develop, cannot be stated. If the latter is the case, the 
lack of correlation is only an index of a diseased or imperfect 
organization, and therefore not in itself responsible for the 
elimination. Crampton’s idea, however, is that the imperfect 
correlation is due to formative factors in the insects themselves 
which leads directly to their death, and not to elimination due to 
external conditions. 
Variation and Parthenogenesis 
The problems of variation and of inheritance have generally 
been studied in animals that reproduce sexually. In only a few 
parthenogenetic forms, namely, in some insects, in aphids 
and in the honey bee, and in the crustacean, Daphnia, 
has the problem of variation been examined. Weismann ad- 
vanced the idea that the purpose of sexual reproduction is to 
