INHERITANCE OF COLOUR IN DIAPHORA MENDICA. 103 



sometimes in the morning and sometimes during the night. There is 

 no very definite hour of emergence as in many species. Pairing also 

 occurred at any time, sometimes in full daylight at midday, at other 

 times near midnight. 



Ova were laid the same day or oviposition was delayed till the 

 third day. Notes on the development of ova and larvte are worthless 

 owing to the artificial conditions under which they were kept. 



Disease was apparently introduced with the food. The early broods 

 always did better than the late ones, though the tins and sleeves were 

 sterilised with the same care and well matured nettle was always 

 chosen. 



There was no evidence that the disease, characterised by weakness, 

 loss of appetite, and slight diarrhtea, was transmitted from one 

 generation to the next, or that the rooms in which the larvse were 

 kept remained infected from one year to the next. 



The only previous experiments on crossing the two races, on 

 which I have read accounts, are those of Caradja and Standfuss. 

 Caradja first crossed S' rustica x ? inendica, but all the larv^ except 

 two died of pebrine. Next year he did much better, and found this 

 cross perfectly fertile, though the mortality from disease was very heavy. 

 He found the reciprocal cross much weaker and only obtained 16% 

 of larvae from it. This vvas confirmed in later experiments. His 

 rustica were from the Caucasus, and this may account for this difference 

 in his results and mine. I found no difference in fertility in the two 

 crosses. Caradja and Standfuss found that the F.l generation of 

 (^ iHstirax ? iiieiulira were intermediate, but nearer to rustica than to 

 )iieiidica. 



The reciprocal cross they found produced darker specimens, 

 whereas the six males which [ obtained were even nearer rustica than 

 those bred from rustica ^ X uiendica J . 



Probably with larger numbers the result of both crosses would be 

 found to be similar. Caradja has named four of the forms he obtained. 

 The very pale forms almost like rustica he calls var. clara, of which he 

 obtii,ined 28%, the pale intermediate he calls var. standfussi, of which 

 he obtained 24%, and the dark intermediate forms var. mas, of which 

 he obtained 38%. 



In my series these three forms merge into one another so evenly 

 that I can see no advantage in giving them separate names, and 

 Standfuss calls them all standfussi. Caradja himself had about 20%, 

 which he could not definitely place under his varietal- names. 



His fourth form, of which he bred three males, he calls ab. uvixta. 

 It had a ground colour like var. clara, with a central cloud over the 

 forewings. This appears to be almost identical with the form of which 

 I bred two specimens, one in 3 916 and one in 1917. It is a very 

 distinct and beautiful aberration. Caradja crossed his var. standfussi 

 with both (^ and ? rustica and uiendica, but does not describe their 

 progeny. He also inbred his standfussi, but only obtained a few weak 

 larvffi. so that his experiments throw no light on the question of 

 whether segregation occurred in the F.2 generation or not. 



Tfje results obtained by Caradja and Standfuss show that the 

 colouring of var. rustica appears more strongly in the F.l generation 

 in the males than that of mendica. This result is confirmed by me, and 

 I found further that it extended to the F.2 and F.3 generations. The 



