Recovery from immersion in water. An index of metabolism and the condition of the gonads in Drosophila melanogaster Meigen and Popillia japonica Newm.

In some insects the selection of individuals which recover in equal periods of time from immersion in water may be used to obtain material of approximately uniform physiological state; Drosophila melanogaster, Meigen, was found to have a mean of recovery for the males 0.97 ± 0.542 minute later than the females, which would indicate a lower metabolic rate for the males. The Japanese beetle, Popillia japonica Newm., was found to have a mean of recovery from immersion in water of both sexes the same in August, while in September the males were retarded by 8.1 as compared with females. This would indicate that the males have and equal me abolic rate in August with the females and a lower rate in September. Carbon dioxide, hydrogen, and nitrogen produce in the flies a condition of asphyxiation similar to immersion in water. [Vestigial] flies recover from immersion in water in a fashion similar to ‘wild’ flies. The recovery periods from immersion in water in the flies can be used to group individuals into those possessing approximately equal egg‐laying capacities and to isolate spent individuals from others still capable of laying eggs. Yeast appears to be more of a stimulant to egg laying than it is to larval growth. Groups of flies which were fed yeast were found to average 71 per cent increase in egg laying over groups of flies that were not fed yeast. The O 2 consumption of the groups of flies actively laying eggs, as contrasted with the groups which were not so active, was found in the former to be 32.9 per cent greater.