H. Onslow 227 



VI. The Orkjinal Material. 



I am indebu»d to tho kindn('.H.s of the lit'v. (J. H. lijiynor for the 

 maU'rial with which the brooding ox|H'riinonts wcr(3 airried out. This 

 strain of lutea origiuatcd in 1J)04 with two pair insectH bred from wild 

 larvae collocU»d in the neighbourhood of Warrington. These in.s(?(!ts 

 were shown to nie : the (f had a value of about [17 : lo], and the J a 

 value of about [1*0 : 18], bein^f only just tinged with yellow. 



Dr Donciwter most generously gave me six families of set insects 

 bred by him between 190()-li)10, and with his permission, 1 have 

 included the data from the^ families with my own. Eiich family bred 

 b^ Dr Donc4ist<?r has been marked with an Jisterisk wherever it (x:curs. 



My original material consisted of two batches of ova sent by Mr Riiynor 

 in 1914. The female piirent of one family ('H B), was a wild insect 

 previously fertilised by a yellow male. The wild $ was aiptured in 

 Milltown Park, Dublin, the locality in which the ''Q variety," described 

 by the Rev. J. M. Woodl(X)k\ w;i8 found. All the F^ generation was 

 therefore heterozygous for yellow. The parents of the other family 

 ('14 A) were described as a " piir of yellows." One of these yellows 

 which I was able to examine had a low colour- value, i.e. [17 : 17]. As 

 a rule, homozygous yellows, as can be seen from Fig. 16, have a much 

 higher value, at least above [2*4 : 24]. Moreover, it will be seen from 

 the pedigree that the male in question wjis bred from a jlampalliata % 

 X grossulariata (f . Consequently it is much more probable that the 

 insect was a yellowish heterozygote, than a homozygous yellow, and 

 therefore the family '14 A is BR x RR, and not RR x RR as was first 

 thought. This view is supported by the fact that of the total offspring 

 (10 c/'c/' ^nd 12 ? J) 11 had an orange value greater than 2*6, and 11 

 an orange value less than 16. The material has therefore been treated 

 in accordance with this supposition. 



The larvae were reared with the usual precautions, great care being 

 taken with the labelling, and every endeavour made to avoid intro- 

 ducing either eggs or very young larvae from one box to another. It 

 seems almost impossible, however, to prevent a larva that has escaped 

 from reappearing occasionally amongst the food when another brood is 

 being dealt with. No doubt a small percentage of errors may be 

 attributed to this cause, as for instance the appearance of some of the 

 palest individuals in the lutea x lutea matings (see Fig. 16). In order 

 to avoid the ill-effects of in-breeding, type insects were obtained for 



» J. M. Woodlock, Journal of Genetics, Vol. v. p. 183, 1916. 



16—2 



