234 INSECT TRANSFORMATION 



of light reflected from the surroundings. These adaptations 

 shown by larvae during the period of their growth are highly 

 interesting and suggestive to those who think of the problems 

 presented by the relation of living creatures to their sur- 

 roundings. The habits of the caterpillars, their form and colour, 

 the changes of hue they undergo, are of the nature of responses 

 to their changing environment. But they are living organisms 

 and the power to respond by outward behaviour and internal 

 reaction is part of the creature's innate constitution ; it could 

 not answer harmoniously to its surroundings had it not 

 inherited the power to do so. The inheritance can be traced 

 to the essential substance in the germ-cells whence the creature 

 sprang. These become mature and functional in the adult 

 winged insect which lives under very different conditions from 

 those of the caterpillar. Yet this germ-plasm is so constituted 

 as to provide for the needs of larval life not only in deter- 

 mining structure and appearance but also in fixing habits of 

 suitable behaviour. Those w r ho believe that the germ-plasm 

 may itself be subject to environmental influence, might remind 

 us that the germ-cells are already undergoing their development 

 within the caterpillar which is identical individually with the 

 pupa and the imago into which it will change. 



This reference to characters inherited through the parents 

 suggests a subject which may fitly close this discussion on the 

 environment of insects during their period of growth. Among 

 many animals the family atmosphere, as it may be called, 

 supplies environmental factors of high importance ; common 

 birds and beasts afford examples of the care of parents for 

 offspring, of the comradeship of brothers and sisters. These 

 factors are not strongly evident among insects as a class, yet 

 they are frequently indicated, and in some well-known cases 

 they are developed with characteristic specialization. Com- 

 radeship between members of the same family is shown by 

 those caterpillars which live on masses of silken web spun by 

 their collective labour. In the pages of this chapter, repeated 

 mention has been made of the egg-laying habits of various 

 female insects, and it is evident that these habits secure 

 suitable provision for the needs of the young during their time 

 of growth. For comparatively few insect larvae have the 

 power of travelling far in search of food ; the newly-hatched 



