in Pedigree Motli-hrecding . 91 



The apparently more rapid development of the female 

 than of the male in illunaria (also, as will have heen 

 noticed, in autumnaria) was unexpected, and probably 

 the experiment has not been on a sufficiently large scale 

 for this apparent result to be relied on. Where there is 

 a difference in priority of emergence of the sexes, I have 

 usually found it rather in favour of the male, so that if 

 the female develops more rapidly in the pupal stage, 

 that would perhaps involve a slower development of that 

 sex in the earlier stages.] 



Effect of cold on yupce of spring emergence. — [I should 

 premise that forcing these, except when it was deferred 

 until they had been some months in pupa, produced 

 very unhealthy results, as shown by the small percentage 

 of survivors and the great proportion of cripples.] 



The observations which immediately follow have 

 relation to the effect of temperature on those pup?e 

 which would in due course emerge in spring. In 

 1887 my second forced brood of mixed iUuUraria (off- 

 spring of about 10 pairs), all hatched between 4th and 

 10th August, and all treated exactly alike, instead of all 

 feeding up, as the iUiuiar'ui had done, split into two 

 divisions ; the first, consisting of 28, pupated rapidly 

 between the 22nd and 30th August, and all emerged in 

 perfect condition between 30th Aug. and 8th September, 

 i. e., in from 8 to 9 days. Of the rest, a few died as 

 feeding larvae, more in pupating, which began 9th Sept., 

 10 days after the others had left oft"; but the majority 

 of them became pupa, and would no doubt, under 

 natural conditions, have remained over until next spring. 

 [This splitting up of a brood into two seems plainly to 

 have been caused by an artificially heightened tempera- 

 ture ; in other words, subjecting the larva to a heightened 

 temperature caused a portion of the brood, which would 

 otherwise have remained over and appeared as moths 

 in the spring and with the spring colouring, to appear 

 as moths in the same summer and with the summer 

 colouring ; i. e., the decisive point was in this case 

 reached in the larval stage, and reached by the appli- 

 cation of a high temperature. I am aware that Prof. 



