ARTIFICIAL PARTHENOGENESIS IN CUMINGIA 9 



larvae that developed from them was counted the next day. 

 If there were no larvae in this lot, but some in the main dish, 

 the number is recorded as 'few.' If there were only a very few 

 in the main dish, that fact is recorded. 



Although the eggs vary greatl}^ in their susceptibility to treat- 

 ment, a tabulation of the experiments shows that the highest 

 percentages of larvae result from an exposure of 60 minutes to a 

 temperature of 32-33°C. This treatment was used in eighteen 

 experiments, of which four failed to produce any larvae and 

 three gave less than 0.2 per cent. Of the remaining eleven ex- 

 periments, ten yielded larvae in proportions varying from 0.2 

 per cent to 4 per cent and in one 18 per cent of the eggs de- 

 veloped to this stage. The unusually successful result of this 

 last-mentioned experiment is an illustration of the variation in 

 the susceptibility of the eggs to the treatment. All attempts 

 to obtain a similar result by repeating the experiment exactly 

 were failures^no one of them gave more than 4 per cent of 

 larvae. One might think that the experiment was contaminated 

 by sperm except for the fact that the control showed no devel- 

 opment, and there was no evidence of fertilization among the 

 eggs preserved from the experiment for cytological study. 



Although 60 minutes is the optimum length of exposure to 

 32-33°C., larvae may be obtained by shorter exposures. Even 

 a 30-minute treatment may give 0.2 per cent larvae, and a 45- 

 minute one may give 1 per cent. Exposures lasting as long as 

 90 minutes also give fair results. To summarize, we may say 

 that out of forty experiments in which this temperature was 

 used, six gave no larvae at all, nine gave less than 0.2 per cent, 

 and the remaining twenty-five gave 0.2 per cent or over. For 

 further details of these experiments, the reader is referred to 

 table 1. 



The next group of experiments is made up of those in which 

 the eggs were heated to 33-35°C. For this temperature the 

 optimum exposure is 30 minutes. This group includes four 

 experiments which were made at the beginning of the study, 

 when no counts were made to obtain the percentage of larvae. 

 Setting these four aside, however, we have the following re- 



