486 MRS. O. A. MERRITT HAWKES ON THE 



found in the pure Red families, where, moreover, the variations 

 of the offspring appear related to those of the parents ; if, how- 

 ever, these variations are the heterozygous forms, one would 

 expect to find some Blacks appearing when these Reds are mated 

 together, but, so far, that has not been the case. A large 

 number of matings will have to be made, as the numerical pro- 

 portions in which the vai'ieties occur in nature indicates that 

 there ave certain points of genetic stability, and that many of the 

 intermediate varieties, if such there are, must have a definite 

 relation to certain parent types. 



The condition in bipunctata may be similar to that observed 

 by Lutz (17) in Crioceris asparagi. He says : " Thus we have a 

 good case of a perfectly graded variation (from spots discrete to 

 spots joined) obeying Mendel's law. Spots joined even lightly 

 and on one elytron only make a ''pure" recessive individual. 

 One of these intermediate forms seems characteristic of the (DR) 

 heterozygous form." 



Six matings as follows were made between Black and Red : — 



m. 20 d" Red x $ 6-pnstulata produced one Red. 



m. 21 (S Red x $ 6-pustulata produced one 4-maculata, one 



6-pustulata, two Red. 

 m. 22 cS Red X $ 4-maculata produced five G-j^ustulata, three 



Red. 

 m. 23 c? Red x $ 6-pustulata produced four 4-raaculata, five 



6-pustulata, two Red. 

 m. 25 d 4-maculata x 5 Red produced one 4-maculata. 

 m. 29 c? Red x $ 6-pustulata produced one 4-maculata, two 



6-pustulata, one Red. 



There is here no sign of dominance, but there is a large pro- 

 portion of Blacks (20) to the Reds (9). This proportion is 

 surprising, as the Blacks are normally in the minority accoi-ding 

 to data so far collected. If the larvae destined to become Black 

 imagines have the same physiological resjDonse to heat as the 

 Black imagines (see section 1), their large pi-oportion might be 

 accounted for. 



So far, only two matings (m. 57 in 1918 and m. 25 in 1919) 

 were made between a Black S and a Red § ; both these produced 

 Black ofi^spi'ing only, so that not sufiicient data is yet at hand 

 to judge if there is a sex factor in the inheritance. 



There are usually two medium posterior whitish spots on the 

 pronotum of the Red form. These may be absent, or the two 

 may be large enough to fuse in the middle line. So far, no 

 regular method of inheritance of these spots has been determined. 

 Palmer (1911) found "the presence of the whitish basal markings 

 on the pi'onotum (of anvectans and melanopleura) dominate over 

 its absence in coloradensis and kumeralis.'^ The degree of the 

 development of these spots is not related to the degree of the 

 ^development of the black dorsal spot in any way ; these white 

 spots are absent in the Black form, the pronotum of the Black 



