164 PROCEEDINGS OF THE ACADEMY OF [Jan., 



section of the Papilios to which he gave the name Pharmacophagus. 

 He maintained that both of them, and the Ithomiince and Acrceince as 

 well, derived their distasteful qualities direct from the larval food- 

 plants. I refer to the following passage in which Dr. Skinner is 

 speaking of Danaida plexippus (33, p. 126) : 



"The protective idea in this case is the same as in the so-called 

 pharmacophagus butterfly, the imago of plexippus which is said to 

 be repugnant to birds but the repugance is not based on the idea of 

 the butterfly feeding on a poisonous plant (Asdepias) in the larval 

 stage." 



As regards the specially protected and much-mimicked group of 

 the Acrceince, the recent hitherto unpublished researches of my 

 friend Mr. W. A. Lamborn upon their larvae in the Lagos district 

 strongly suggest that the butterflies do not derive the nauseous 

 qualities, which they undoubtedly possess, in the manner assumed by 

 Haase; for the food-plants belong to varied groups. In a letter 

 written July 16, 1913, and received as I am preparing this paper, 

 Mr. Lamborn states: "By far the most common Acr(Ea here [the 

 neighborhood of Ibadan, S. Nigeria, W. Africa] is terpsichore. Its 

 larvse abound, and seem, like so many other distasteful caterpillars, 

 to have a wide range of food-plants." 



The facts brought forward by Dr. Skinner do not appear to me to 

 affect the probability of Haase's hypothesis. It is well known that 

 insects feeding on a great variety of plants commonly include among 

 these species with poisonous quahties. Haase's hypothesis only 

 refers to certain insects confined to poisonous or acrid food-plants. 

 I say "certain" insects, for the power of utilizing the poisonous 

 quality, if it exist at all, is undoubtedly a special adaptation by no 

 means necessarily present in any larva which feeds on the plant 

 possessing the quality. The other fact alluded to by the author, 

 that the acrid principle may be present in very small quantity, is, 

 I think, equally devoid of bearing on the hypothesis. If the adapta- 

 tion exist at all, we should expect small quantities to be stored up and 

 concentrated. The percentage of lime in a leaf is very small, yet the 

 larva of Clisiocampa neustria reserves enough to render its cocoon 

 opaque with minute crystals of the carbonate in the form of aragonite 

 (5) and Eriogaster lanestris enough to make its eggshell-like cocoon 

 out of the oxalate (8). 



Haase's hypothesis cannot be proved or disproved by discussion. 

 It is the work of the chemist that is needed. The most appropriate 

 field in the world for this work is North America with its hundreds 



