The utilisation of derived plant-pigments in the 

 ccoLOQRiNG OF Lepidoptera. — Prof. PouLTON drew attention 

 •to a paper on " Blue-Green Caterpillars," published November 

 1921, in the "Journal of Experimental Zoology" (Vol. 34, 

 No. 3, p. 385), by John H. Gerould, Dartmouth College, New 

 Hampshire. In the course of the author's breeding experi- 

 ments, on Colias philodice Godt. about 45 blue-green cater- 

 pillars * appeared among about three times as many of the 

 usual yellowish grass-green colour. Corresponding differences 

 were seen in the pupae and in the eyes of the imago. The 

 eggs laid by a female with blue-green blood (haemolymph) 

 and eyes were pure white as compared with the normal cream- 

 white. The empty pupal shell was pure white as compared 

 with golden yellow. The cocoons of a Braconid parasite 

 {Apa7ifeJes flaviconchae Riley) were pure white when the host 

 was blue-green, bright yellow when it was yellow-green. 



The interpretation was found in the fact that the blue- 

 green caterpillars were unable to utilise the yellow constituent 

 (xanthophyll) of the green colouring-matter of their food- 

 plant (clover), but utilised the blue-green constituent (chloro- 

 phyll), while normal caterpillars utilised both. These derived 

 pigments, present in a modified state in the blood or in the 

 tissues or in both, accounted for the above-mentioned colours 

 in the different stages, the yellow constituent being especially 

 penetrating and especially persistent, for it alone reached the 

 cuticle and it alone appeared in the Braconid cocoons. 



The author also proved that the bluish tint is a Mendelian 

 recessive and the yellowish dominant, but for the convincing 

 (evidence and many interesting details the paper must be con- 

 sulted. A copy, by the author's kindness, has been presented 

 to the Society. 



In a later paper, read at the recent meeting of the American 

 Assoc, for the Adv. of Sci. at Toronto, and kindly sent to Prof. 

 Poulton in typescript, Mr. Gerould described an olive-green form 

 of the same larva, recessive, like the blue-green, to the yellow- 

 green. The olive-green effect was due to the pigment in the hypo- 

 dermal cells, the blood being indistinguishable from that of the 



* The blue-green caterpillars were also entirely without the pink 

 line running along the centre of the spiracular >vhite band. 



