374 JOHN F. FULTON, JR. 



an effort to find the origin of the fat glohules in the crustacean 

 chroniatophores. The investigation proved that the carotin 

 present in these cells produces the fat globules by photo- 

 synthesis. The work was carried out on Hippolyte 

 V a r i a n s , and the experiments were briefly as follows : ^ 

 when Hippolyte is starved in the dark practically all of the oil 

 disa])})ears from the chroniatophores ; when starved in sun- 

 light, however, the globules continue to exist as before ; when 

 a ' dark-starved ' Hippolyte is exposed to sunlight (without 

 feeding) the fat returns. Thus the crustaceans present a remark- 

 able phenomenon : tlu^ plant pigment which has been eaten 

 by the animal, is stored in the liver ; later it is carried by the 

 blood-system and deposited in the epidermal chromatophores, 

 where it functions exactly as in the plants from which it was 

 derived ! The only othtu- instance of such a phenomenon 

 known to the writer is that (already referred to on p. 373, note) 

 described by Palmer and Eckles (1918), who have shown that 

 carotin and xanthoi)liyll pass in the blood from the intestine to 

 the mammary glands. It is extremely interesting, also, to note 

 the recent observation of Findlay (1920), that carotin and 

 xanthophyll are found in the mammalian adrenals, and are 

 largely responsible for the colour of the glands. 



(b) The Insecta. 



In many ways the insects offer a more favourable condition 

 for the study of animal pigments than any other group of 

 animals. They are small, many are brilliantly coloured, and 

 in addition the physiological processes of insects are on the whole 

 less complicated than in other forms ; moreover the more 

 important pigments of insects are concentrated in the wings, 

 which are thin and therefore well adapted for the purposes of 

 observation. 



The greater share of the work on the pigmentation of insects 



^ It is not within the scope of this paper to attempt to summarize Keeble 

 and Gamble's results on the mechanism of colour change in this animal. 

 They will be found in the papers cited above and in Gamble (1910) ; a more 

 recent study of colour variation in crustaceans is that of Potts (1915). 



