COLOKATION AFFECTED BY THE ENVIRONMENT. 53 



couteuting themselves witli other allied food materials, and so 

 give rise to varieties whose origin we do not dream of, and 

 which therefore we are led to regard as new species ? " 



The effects of food upon the colour of the imago or perfect 

 insect do not in these cases, curiously enough, affect the larva ; 

 it would seem to be the larva which ought to be altered before 

 the imago. There are, however, examples of a connection 

 between the coloration of the larva and the imago. 



Mr. Jordan * observed that whitish larvfe of Sphinx populi 

 (the Poplar Hawk moth) gave rise to albino moths ; on the 

 other hand, melanic caterpillars of the Magpie moth resulted 

 in imagos which were not specially black. 



That the yellow colour of canaries can be altered to an orange 

 red by mixing cayenne pepper with their food, has been known 

 for a long time. This curious fact was first discovered in 

 England, as was also the fact that the different races of canaries 

 vary in their susceptibility to the action of the pepper ; some 

 kinds are more, others less, affected, while one race is absolutely 

 without any power of having its coloration altered by these 

 means. The colour change is produced by feeding the newly 

 hatched yoimg with the pepper conveyed in their food or the 

 old birds while sitting upon the nest are furnished with food 

 containing the cayenne, with which they in turn feed their off- 

 spring. The colour change can, in fact, be only brought about 

 in very young birds whose feathers are not completely matured; 

 it is quite impossible to produce any alteration upon the full- 

 grown canary. Clearly, therefore, here is an instance of the 

 direct effect of food upon colour. An interesting paper upon 

 the subject, which has also furnished me with the facts already 

 mentioned, has lately appeared,t and it will be of interest to 



* Ent. Monthly Mag., vol. i., p. 63. 



t " Archiv. Anatomie und Physiol." 1S89 : Physiol., Abtheil. 543. 



