H. Onslow 55 



though none of the pairings were fertile. The other paired 5 times, the 

 first two pairings being sterile and the last three pairings fertile. The 

 female does not often pair twice, but I have more than once seen this 

 occur, though in breeding the female is usually isolated as soon as 

 fertilized. 



The appearance of the type and melanic insects in the following 

 experiments is shown on Plate II. The melanic females are a deep 

 black (figs. 4 and 5), the melanic male is rather browner (fig. 6), the 

 antennae being very slightly pectinated. In both sexes the veins are 

 traced in deeper black, especially noticeable when freshly emerged. The 

 characteristic " square spot " between the second and third submarginal 

 lines is naturally invisible, but usually a pale wedge-shaped marking, 

 more pronounced in the female than in the male, makes its appearance 

 just at the inner margin of the square spot. The only other white 

 marking is a faint wavy line on all four wings, which in the type insect 

 is situated at the outer margin of the square spot. All the type insects, 

 extracted from melanics, were greyer and less ochreous than is usually 

 the case with wild individuals. This is especially noticeable in the 

 female (figs. 1 and 2), in which the speckling is grey and many of the 

 markings black. The males tend to be browner and the markings are 

 slightly blurred and indistinct. Fig. 3 represents one of the darker 

 males, but none of these in any way approached the melanic series. 



I am indebted to Mr L. W. Newman for procuring me the melanic 

 ova for experimental purposes, and it is with his permission that I publish 

 the following details. In June 1914 a wild melanic $ and several 

 type t/c/ were taken in the oak wood at Wateringbury. After capture, 

 the $ deposited ova, and from the larvae which resulted, three melanic 

 insects emerged in 1915, 2 ^ $ and 1 (/. With these, three fertile 

 pairings were obtained, the melanic ^ pairing twice ; the larvae all did 

 well and the following insects emerged in 1916 : 



Parentage Imagines 



Totals 316 



The larvae were not kept under experimental conditions, and the four 

 type insects recorded were possibly introduced by accident. The fact 

 that no type insects appeared in families '15 A and '15 B suggests that 

 the melanic parents were homozygous for the melanic factor. If this 



