260 Proceedings of Indiana Academy of Science 
February 26, 1913, when she became very feeble and was accidentally 
killed. ; 
Attention is called to the fact that this fly often produced her 
weight in eggs during the course of 24 hours, and throughout her life 
she averaged her own weight in eggs every two days. The calculations 
are based on the following data: 
(1) Determination of the weight of the egg of Drosophila before 
and after drying. A number of eggs were carefully picked with a 
needle from a mass culture and weighed. They were dried at 37° C 
for four days and again weighed. The weights are recorded in table 2. 
The average weight of the egg before drying is 0.0180 milligrams and 
after drying 0.0111 milligrams. 
TABLE II. 
This table gives the weight’ in milligrams of eggs of Drosophila melanogaster, before and after dryimg. 
1919 No. of Weight before drying Weight after drying 
ezgs | at 37° C for 4 days. 
Dec 
5 100 ye) | i Prarie 
6 100 Bio 1.5 
18 112 2.5 Ld, 
19 100 1.3 0.6 
21 110 1.3 0.9 
TOEALs. 2 ok 522 9.4 4.7 
Average 
weight..... 0.0180 0.0111 
| 
| 
| 
(2) Determinations made for 204 newly emerged females gave 
an average weight before drying of 1.2436 milligrams, after drying at 
37° C for five days the average weight per fly was 0.305 milligrams. 
The average weight of 128 newly emerged males, 1.0601 milligrams; 
after etherization and drying for five days at 37° C, their average 
weight was 0.300 milligrams. The flies of this species vary greatly 
in size, depending upon cultural conditions. The determinations are 
here made for animals of average size. 
When one computes the total weight of the 2,184 eggs laid by female 
number 8 in terms of the average weights of eggs and females here 
found it is demonstrated that this fly laid 32 times her weight in eggs. 
If account is taken of the dry weight of the fly and the dry weight of 
the egg then she laid approximately 80 times her weight in eggs. This 
is a striking physiological performance. 
The fecundity record is apparently not modified as a result of 
fertilization for the unfertilized female lays eggs regularly and in 
large numbers. However, when the flies are kept in large numbers in 
the same bottle the females do not lay as many eggs on the average 
as when kept separately, despite the fact that on the average a 
larger egg laying surface may be exposed for each fly in the crowded 
culture. Johns Hopkins University. 
