( lix ) 



larva?, now feeding, some few being nearly fall-fed. The 

 forced second generation was distinctly larger than the same 

 generation sleeved, and each successive forced generation 

 showed a measurable increase in size over its predecessor. 

 From the forced second generation he had selected A, M, 

 and Z pairs, from each of which he had reared a number of 

 moths, but the A's and Z's in this third generation failed to 

 produce fertile eggs, though several pairs of each were tried. 

 The M's produced abundantly, and from one of these M pairs 

 he bred 61 moths, from which he had again selected A's, 

 M's, and Z's, which laid fertile eggs, and from these pairs 

 he had the three broods of larva? above referred to as now 

 feeding, some of which he exhibited. He refrained at present 

 from any inferences as to the cause of the sterility of the 

 third generation of forced moths in the A, M, and Z lines, 

 but thought it would be prudent in continuing these experi- 

 ments to include some selections from points considerably 

 short of the extremes in size. All the successive generations 

 were of the summer type (Juliaria). In all the female was, 

 on the average, sensibly larger than the male, but in the 

 natural spring emergence the reverse was the case. S. iUiinaria 

 was the only English double-brooded Geometer, except per- 

 haps T. laricaria, which had one of its emergences in a winter 

 month, and he threw out the suggestion whether the relatively 

 smaller size of the female in the first emergence might be a 

 step towards or a remnant of apterousness, usual in the 

 female of our winter moths. It would be interesting to breed 

 and compare T. laricaria. He could not undertake any other 

 species than illunaria and ill \ustr aria, and circumstances might 

 interfere even with them ; and as the experiments with them 

 must continue for many generations in order to reach the 

 results wanted for Mr. Galton's purposes, and required un- 

 interrupted watchfulness, it was essential, to prevent an 

 accidental failure, that there should be a second line of 

 experiments conducted independently. Both species were 

 very easy to rear, and offered much scope for experiment in 

 various directions ; he would gladly supply eggs in the spring 

 for the purpose. Mr. Merrifield further said he should 

 be glad to be afforded the opportunity of seeing and, if 



