114 CARNEGIE INSTITUTION OF WASHINGTON. 



The mother of this brood {¥^ female) could not roll up her tongue. Of 

 her 65 offspring about one-half are normal, one-half can not roll up the 

 tongue, i. e., 28 normal, 37 uncoiled. In the males the equal ratio obtains: 

 18 normal, 20 uncoiled; in the orange females, 5 normal, 6 uncoiled; in the 

 white females, however, 5 normal, 1 1 uncoiled. These numbers indicate on the 

 Avhole a regular heterozygous condition as regards abnormality of tongue. 



Two white eurytheme females (a^^ female and 6^^ female) were crossed 

 with philodice male, which bears no orange (pale sulphur yellow). This 

 family, o, is as follows: males 72, females 71 (white 36, orange yellow 35). 

 The hybrids are somewhat intermediate in color between the two species, 

 showing dominance of orange, though the orange suffusion upon the yellow 

 background is reduced in extent in the hybrid. The other family, p, con- 

 sists of 11 males, 7 females (4 white, 3 orange-yellow). 



The white species-hybrids are almost or quite indistinguishable from the 

 albinic C. eurytheme, but I have not yet studied them in detail. 



The male gynandromorph that appeared in family a (a^^) is the son of a 

 white female X wild male. The 57 other males of this family and 53 

 females are normal. Three wings of this individual bear the male color- 

 pattern, but the right anterior wing has the color-pattern of the female 

 (wide, spotted marginal band) with a ground-color of orange and of white 

 in a mosaic, thus shoAving the influence of both of the female color varieties. 

 The male external genitalia are perfect, but crowded to the left side of the 

 median plane. The testis was well developed. No ovaries were found, but 

 there is an imperfect development of the female external genitalia on the 

 right of the posterior end of the abdomen. 



I had obtained in 1912 (October to December) almost exclusively females 

 from the cross between eunjtheme female X philodice male — 20 females, 2 

 males. Repeating this work shows (family o) exact equality between the 

 sexes (72 males, 71 females). However, in the hybrid broods of 1913 the 

 usual precocity of the male is seen to be upset by the crossing of the two 

 species; 7 out of the first 9 to emerge (first two days of emergence) were 

 males. I have thought that this upsetting of the usual precocity of the males 

 may be connected with the apparent partial sterility of the species-hybrids. 

 The females, after mating with male species-hybrids, have in many cases not 

 shown an inclination to lay, though they are invariably full of mature eggs. 

 The males may be in some cases sterile. I am still studying this matter. 



I raised a brood of pure ewr^/^/ie/we from a wild female ; it consisted of 214 

 males, 206 orange-yellow females. Many pupae of this brood were iced, 

 and I tried to mate the resulting adults, but without success, to determine 

 what effect cold might have upon the germ-plasm. There were few males that 

 emerged from the iced pupae, 15 pupae having been killed by the conditions 

 in the refrigerator (excessive cold and perhaps dryness). I shall try this 

 again. This large family ought to throw some light on the matter of varia- 

 tion within the species, since it contains examples of varieties ariadne 

 (pale orange) and keewaydin (deep orange) regarded by some entomologists 

 as seasonal variations. 



I want to extend my experiments eventually by breeding C. edusa and 

 hyale from Europe and the American species, especially C. interior of Canada, 

 the nearest species to C. philodice and eurytheme geographically. C. interior 

 has not been bred, and its food plant is said to be unknown, though I should 

 be surprised if it would not lay on white clover. Species of the genus 

 Colias, although very susceptible to disease and hence difficult to raise, 

 are full of interesting possibilities in the study of the origin of species and 

 heredity. 



