1914.] NATURAL SCIENCES OF PHILADELPHIA. 163 



divisible into three well-marked sections differing in larval, pupal 

 and imaginal characters. They give descriptive titles to each of the 

 sections, but do not suggest names which can be used at any rate 

 provisionally as genera. In the meantime, it is highly inconvenient 

 to include in the genus Papilio the species of all three groups. For 

 this reason, and for this reason alone, I provisionally adopted Haase's 

 Pharmacophagus for the "Aristolochia swallowtails," his Papilio 

 for the ''Fluted swallowtails," and his Cosmodesmus for the "Kite 

 swalloA\i,ails." 



I am quite ready to abandon any or all of these when it is proved 

 that the three groups may be referred to by other names with a 

 prior claim, and, under any circumstances, Haase's terms cannot, 

 with their present meaning, permanently stand for genera, because, 

 as I learn from Dr. Jordan, each of the three sections is a much 

 larger group which must itself be split up into genera. Furthermore, 

 I do not, as Dr. Skinner states on p. 124, accept any conclusions or 

 use any argument based on the meaning of the word when I pro- 

 visionally employ ^'Pharmacophagus" as the name of a genus of the. 

 Papilios, and I do not think that any words of mine can be quoted 

 which will bear out Dr. Skinner's interpretation. 



Inasmuch as Haase's hypothesis occupies so large a place in 

 Dr. Skinner's memoir, I venture to offer a few remarks upon the idea 

 itself as well as upon some of the author's criticisms. 



The great majority of the pigments possessed l^y plant-eating 

 insects are built up in the laboratory of the living organism, in spite 

 of the fact that the larval food is rich in chlorophyll. Nevertheless, 

 this color exists ready-made, and certain insects have been specially 

 adapted to avail themselves of it and thus to gain certain pigments. 

 I proved this many years ago by spectroscopic examination as well 

 as in other ways (3, 4), including experiments in which larvae were fed 

 upon parts of leaves devoid of chlorophyll (lO) — experiments recently 

 repeated with confirmatory results upon different species by Prof. 

 W. Garstang (34). I think it probable that nauseous or poisonous 

 substances, when they exist in a plant or in a group of allied plants, 

 may be employed by certain species which are restricted to it or 

 them; but as yet the proof is wanting. Among the most probable 

 instances, and those which should first be tested by chemical means, 

 are the Danaince feeding on the Asclepiads and the ''Pharmacophagus" 

 swallowtails feeding on Aristolochia and its allies. I may here 

 remark that Dr. Skinner is mistaken in supposing that Haase in his 

 hypothesis drew any distinction between the Danaince and the 



