METACHEMOGENESIS IN INSECTS — ROCKSTEIN 283 



oxidase activity, size of thoracic muscle sarcosomes and flight abiUty 

 (as measured in terms of duration of flight and wing-beat frequency) 

 all become maximal by the sixth day of adult life. In the blow fly, 

 Phormia regina, the size, dry weight and cytochrome c titer of such 

 sarcosomes, as well as wing-beat frequency reach maximum levels on 

 the seventh day after adult appearance. 



In the matter of degree of development of endocrine function at 

 adult emergence, Scharrer (personal communication, 1956) has 

 pointed out that the corpus allatum, especially, shows considerable 

 variation in extent of maturation, from species to species, at the 

 "moment of emergence." In addition to the fairly extensive literature 

 linking maturation of the ovaries of adult insects to corresponding 

 development of the corpora allata (Pfcifl^er, 1945, Thomsen, 1950, 

 and Wigglesworth, 1954), evidence has been cited above for variation 

 in time of completion of maturation of the corpora allata of different 

 species and even between sexes in one species in relation to other body 

 functions, like fat body and oenocyte development and total body 

 metabolism. This seems to be true for the prothoracic glands of dif- 

 ferent species, as well. Thus, this gland (or its homologous struc- 

 ture), which secretes (the moulting and) the growth and diflferentia- 

 tion hormone, disappears within 24 hours after "metamorphosis" in 

 the bug Rhodnius, whereas in Periplaneta americana the prothoracic 

 glands persist for at least 2 weeks after the final moult. 



A recapitulation of the numerous data and observations presented 

 above indicates that there indeed exists a continuity from the juvenile 

 stages into the adult stadium in holometabolous as well as hemi- 

 metabolous insects, which is especially evident in the continuation of 

 biochemical maturation for a considerable time after the last moult. 

 This period of metachemogenesis can only be reflective of maturing 

 adult functions, which are incompletely developed at the time of adult 

 emergence in the case of Holometabola (to a greater or less degree 

 in different species of insects). 



LITERATURE CITED 



Allen, W. R., and Richards, A. G. 



1954- Oxygen uptake of muscle homogenates from three species of insects, 

 in the presence of added succinate, cytochrome c, and phosphate. 

 Canadian Journ. Zool., vol. 32, pp. 1-8. 



