60 THE ENTOMOLOGIST. 



PEDIGKEE MOTHS. 



In a paper upon Pedigree Moths, read before the London 

 Entomological Society, February, 1887, Mr. Francis Galton, 

 F.E.S., explained the plan and object of his proposed experiments 

 in breeding moths, with the view of obtaining certain hereditary 

 data needed to confirm results gained in the course of previous 

 experimental research, when other subjects than moths were 

 treated. 



The substance of Mr. Galton's remarks had, some days 

 before the meeting of the Society took place, been printed and 

 circulated among members; and it is an abridgment of this 

 circular rather than a digest of the paper itself that is now 

 brought before the readers of the ' Entomologist,' — some of 

 whom may not, so far, have heard anything of Mr, Galton's 

 contemplated investigation,— in the hope that some among them 

 may be in a position to assist Mr. Galton in his enquiry, either 

 by furnishing ova of the moth required or perhaps valuable 

 suggestions, the practical outcome of their experience in moth 

 breeding. Mr. Galton says : — 



" It is intended in each case to procure broods through a 

 succession of selected specimens, along three lines of descent 

 from a single pair of individuals, so that there would be three 

 parallel broods in each generation. The particular characteristic 

 that is selected for these experiments must admit of being 

 accurately measured, in other respects the choice is immaterial. 

 For brevity of explanation I will suppose it to be size. Then, 

 starting from the brood of the original pair : — (1) A few of the 

 largest of either sex would be separated and mated ; out of their 

 progeny a few of the largest would again be taken and mated, and 

 so on, for several generations. (2) Exactly the same process just 

 described would be gone through, after substituting throughout 

 the words ' medium- sized ' for ' largest.' (3) Similarly, after 

 substituting the word ' smallest ' for ' largest.' 



" The result will be to obtain a precise measure of the 

 diminution of rate at which a divergence from the average of the 

 race proceeds in successive generations of continually selected 

 animals. The rate during the first few generations is probably 

 the same, whatever may be the characteristic observed (whether 



