48 Trans. Acad. Sci. of St. Louis. 
SAMTA CECROPIA. 
Table 27 presents the data of the fertility of the River 
des Péres Cecropias coming from the normal cocoons. 
We have 9 insects recorded above which mated from 
4to6hours. A glance at the total column promptly tells 
us that the per cent of infertility is so low that the egg 
masses may be called practically all fertile. These pairs 
were artificially separated after having been together 
for 5 or 6 hours, or in one case 4 hours. 
In connection with the normal period of copulation, 
15 to 18 hours, we have 11 insects which show the per 
cent of infertility to be correspondingly low. On the 
whole, this entire lot of eggs were very fertile; the 4704 
eggs included only 106 infertile ones, or 2.2%, while 
97.8% of the aggregate were fertile. 
We cannot see any perceptible difference in’ the fer- 
tility of the early or late deposition, but the smallness of 
the per cent of the infertile eggs in the total deposit 
would make it an increasingly delicate task to detect 
such a difference. This year’s material shows a much 
higher degree of fertility than that for the year 1911. 
In the total F. U. column of the table is given the num- 
ber of eggs in which the embryo partially developed but 
for some unknown cause died in the shell. These con- 
stitute 3.8% of the whole number of eggs deposited, and 
4% of the fertile eggs, a far smaller proportion than the 
1911 eggs, which showed 11% and 14.5% respectively 
unhatched though fertile. 
Here we see clearly that a shortened period of mating 
does not reduce the fertility of the eggs; that the insect | 
could economize on time spent in copulation and _ still 
cause no reduction in the progeny, or that in some cases 
she might even increase the number of her offspring by 
utilizing this extra time for oviposition, in which she 
might otherwise be eut short. 
