the Growth and Habits of Carausius morosus. 351 



Incubation under Diverse Conditions. 



In order to test the method of incubation above described 

 I experimented as follows : — Three lots of eggs were taken, 

 which had been dropped by the same set of insects in the 

 same twenty-four hours on three different occasions. One 

 lot was placed in the usual hatching-box (B) just described, 

 the second lot on the surface of sand (S), and the third lot 

 on the surface of mould (soil) (M). Moisture was con- 

 veyed to the sand and mould by occasional light sprinkling, 

 but mostly from below by means of a dipper. In the 

 course of the incubation some of the eggs sank below 

 the surface of the sand and mould. The nymphs from the 

 sand and mould had, on emergence, access to water, but 

 those from the box had not, and probably in consequence 

 of this we find the box produced on an average shorter 

 nymphs than the sand and mould, thus : M's average 

 = 124 mm., S's = 11*9 mm., and B's 1T2 mm., but, in 

 view of the results of observations on the extension of 

 nymphs after hatching out, this is of little importance. 



In so far as duration of incubation is concerned (Table III) 

 the mould gave the quickest results, the nymphs hatching 

 out on an average in 124 days with a range of 31 days 

 (115-146), against the sand's average of 146 days with a 

 range of 54 days (131-185), and the box's average of 151 

 days with a range of 31 days (141-172). 



Table III. — Incubation under divers Conditions. 



