METACHEMOGENESIS IN INSECTS — ROCKSTEIN 279 



for 3 days after emergence, during which period its degeneration was 

 paralleled by the increase in size of the adult fat body of Sarcophaga 

 securifera Villeneuve; Evans (1935) had made similar observations 

 for the larval and imaginal fat body of Lucilia sericata Meigen. Day 

 also noted that the oenocytes, barely conspicuous at emergence time, 

 increase in size along with the adult fat body during the early days 

 of adulthood, after which they appear to remain histologically and 

 histochemically unaltered throughout adult life. Day demonstrated 

 the dependence of the adult fat body and oenocytes upon the secre- 

 tions of the corpora allata for their maturation in both 6'. securifera 

 and L. sericata by a series of experiments, as follows: Allatectomy 

 of the newly emerged adult results in the failure of the larval fat body 

 to disappear and of the imaginal fat body and oenocytes to develop. 

 Allatectomy of flies even as old as 6 days of age had a regressive effect 

 upon the already formed oenocytes, but not upon the fully formed 

 imaginal fat body. 



In a direct study of the corpora allata, Pflugf elder (1948) found 

 that the volume and nuclear number of the corpora allata of the drone, 

 worker, and the queen honey bee, Apis mellifera Linnaeus, increased 

 in a geometric progression after each larval moult. With "pupation," 

 these values were halved, but again doubled with adult emergence. 

 After emergence, this increase in volume continued in all three castes, 

 with the worker attaining a considerably higher maximum corpus 

 allatum volume than the queen or the drone. Lukoschus (1956) con- 

 firmed these findings in the queen and worker honey bee corpus al- 

 latum, but extended the study of these changes well into the imaginal 

 life; for the queen bee he found a doubling of the corpus allatum 

 volume to occur by the end of the second year of adult life ; for the 

 worker this volume was increased five times within 21 days after 

 emergence, at which time its value was about 20 percent higher than 

 the highest volume attained by the average queen at 2 years of age. 

 Pflugfelder inferred, from this observed growth of the adult corpus 

 allatum in general and especially from the considerably higher activity 

 of the corpus allatum of the sexually inactive worker bee, that such 

 maturation of the corpus allatum is not exclusively related to its 

 gonadotrophic effects. 



The means by which the corpus allatum produces its effects upon 

 other organs as well as upon the ovaries has been suggested by the 

 studies of Pfeiffer (1945) in a paurometabolous insect and by Thoni- 

 sen (1950) in Calliphora erythrocephala. Their work, as well as that 

 of Day (1943), cited above, clearly suggests that the corpus allatum 



