I02 SECTIONAL ADDRESSES 



Although the green forms combine the colours of the other two, they are 

 not hybrid products, but the original stock from which the blue and the 

 orange forms have descended, the blue form having originated by the loss 

 of the yellow pigment, and the orange one by the loss of the blue structural 

 colour. A gradation of the loss of the yellow pigment is observed in the 

 three subspecies from the Bismarck Islands : the green bornevianni 

 Pagenst., from New Britain, with the metallic green scaling similar in 

 distribution to the scaling of the blue New Ireland specimens, a second 

 subspecies, miokensis Ribbe, from Miotio, intermediate in geographical 

 position and in the blue-green colour, and the deep blue urvilleanus 

 Guer., from New Ireland, New Hanover and the Solomon Islands 

 (which has occasionally one or two golden dots on the hindwing). This 

 case of great outward contrasts with so simple an explanation of them is 

 probably unique. ^^ 



In the vast majority of species the geographical differences are quan- 

 titatively small and frequently so concealed (or even inside the body) as to 

 exclude the idea that a process of selection through enemies takes place 

 in such cases. This elimination of one factor in their evolution, however, 

 does not answer the question how these small differences have arisen and 

 become hereditary. A new subspecies being the old plus the surviving 

 and accumulating effect of mass and energy of the environment, perhaps 

 observations of another kind give a hint. In an instance here and there 

 it has been found that the larvas of a Lepidopteron, usually monophagous 

 on a definite plant, through force of circumstances or accidentally feed 

 upon another species of plant, and that then the offspring of this brood 

 will rather die than take to the normal food-plant of the grandparents. 

 Does it not look as if here a habit had become fixed in one generation .'' 

 Now, if we look upon the component parts of an insect specimen as if 

 each part were an individual and apply the above observation, it is quite 

 conceivable that in a new environment one or the other factor affecting 

 the development of the growing body will stimulate this or that individual 

 organ, or group of cells, or retard its development, and when an accelera- 

 tion or a retardation has taken place in one generation, a predisposition, 

 a habit, is acquired by that organ which will persist, like the habit of 

 eating the strange plant. The crested lark, which is common on the south 

 shores of the Channel, but never crosses the twenty odd miles of water, 

 except by accident (about half-a-dozen specimens being known from 

 England), teaches us that habit is a pertinaceous factor in life. 



From the remarks to which you have so patiently listened it must have 

 become clear what my attitude is towards the staff to whom the study of 

 systematics is to be entrusted in public institutes. If I could carry out 

 an ideal, I should leave the preliminary work only to less thoroughly 

 trained members of the staff and continue to appoint for research work 

 the best brains to be got, trained at the University in scientific thinking, 

 who do not merely float, but can dive. 



'^ Incidentally it may be mentioned that green specimens of P. priamns which 

 have suffered from damp assume a bluish tone in consequence of the deterioration 

 of the yellow pigment. 



