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Mr. G. Smith. 



glycogen material (fig. 5), while the reddish -orange individuals which have 

 been crowded at a lower temperature have the greater part of this glycogen 

 replaced by orange globules of fat. This does not apply to the small 

 granules in the skin and gut, which are invariably present in all categories of 

 individuals, but to the subdermal connective tissue masses round the gut and 

 at the bases of the limbs. The connective tissue cells which store the 

 reserve material have thus two alternatives : they may store glycogen, as in 

 the case of the pale translucent individuals, or they may store preponderantly 

 fat, as in the case of the crowded individuals at low temperatures. 



By following the course of events occurring in the parthenogenetic females 

 under the conditions of isolation at 27° C. and crowding at 10-17° C, it can 

 be shown that the quite young individuals soon after birth in both cases have 

 their reserve material distributed typically in the way shown in fig. 6. There 



Fig. 6.- — A young parthenogenetic female, showing distribution of glycogen and the few 



large fat globules. 



are a few large globules of fat, represented by the dark circles, and a large 

 supply of glycogen at the bases of the limbs. Now, as growth proceeds, the 

 individuals kept isolated at 27° C. retain their reserve material in the form 

 of glycogen and do not develop fat in any quantity (fig. 5) : they grow and 

 moult very rapidly and may reach maturity in three or four days. The 

 individuals kept crowded at 10-17° C, on the other hand, tend to lose their 

 glycogen deposits and to deposit large quantities of fat, and they grow and 

 come to maturity much more slowly than the isolated individuals at 27° C. 

 It is important to note here the coincidence of glycogen storage and rapid 

 growth on the one hand, and of fat storage and retarded growth on the other. 

 Now the question arises, is it possible to connect this difference in behaviour 



