486 TRANSACTIONS OF THE CANADIAN INSTITUTE. [Vou. VIII. 
of different ages were suspended over water, each cluster in a wide-mouthed 
bottle the cork of which had two shallow grooves cut down the sides to 
admit small quantities of air. ‘The bottles were kept in a cellar where 
the temperature was practically the same as that of the natural situation 
of the eggs. In all the clusters development proceeded without inter- 
ruption, in some cases for as much as twenty-five days when an impending 
absence from the laboratory rendered it necessary that the experiments 
be terminated and the larve were fixed. About eight per cent. of the 
larve always die under this artificial incubation, in some bunches no 
deaths at all occurring, in others several. This is quite striking, for no 
unfertilized eggs or dead larve were ever found under natural conditions. 
Three things may account for this; injury in conveying to the laboratory, 
the growth of mould during incubation, and lack of the normal increase 
of fluid between the egg and the inner envelope. Mould on the eggs 
although never encountered under natural conditions sooner or later 
makes its appearance on all eggs reared as above described. It does 
not however always have an early fatal effect, for all the larve in a bunch 
have been found alive after having been quite obscured for two days bya | 
growth of mould. The increase of fluid between egg and envelope can 
hardly be said to occur under these artificial conditions and presumably some 
pressure is exerted upon the larva. These things suggest that the female 
may in some way prevent the growth of mould on the eggs and also supply 
them with moisture and an endeavour was made to test this in the following 
way. In a wide-mouthed jar pieces of the log in which the eggs were 
found were arranged to form a little chamber in which the female was 
placed and the piece suspending the eggs then added as a roof; more 
fragments were placed upon this and the surface covered with a little 
humus and moss, a few drops of water were occasionally sprinkled on the 
surface. Jars so prepared were kept under the same conditions as the 
bottles previously mentioned for three weeks, by which time mould 
would certainly have appeared on eggs kept in bottles, but none was 
found, and the amount of fluid surrounding the larva was as great as 
natural. In a subsequent set of experiments it was found that even 
thoroughly wetting the cluster two or three times a day, in addition to 
keeping it over water as before, would not suffice to bring about the nor- 
mal accumulation of fluid. This was only obtained by allowing the lower 
end of the cluster to remain in contact with the surface of the water in 
the bottle for about twelve hours out of each twenty-four. 
No final statement should be based on such scanty experimental] 
evidence but such weight as it has is entirely in support of the supposition 
that the mother in this case—and presumably in similar cases reported 
