278 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 1 37 



in mean diameter by two and one-half times during the first 7 days 

 of adult life ; as can also be seen in figure 12 the wing-beat frequency 

 of D, funebris (as an index of flight ability) parallels these data for 

 change in sarcosome size in the same species. Thus for two different 

 dipteran species there is strong correlative evidence from several lines 

 of investigation for postemergence maturation at the subcellular level. 

 As part of a recent study of the respiratory metabolism of fly 

 sarcosomes British biochemists Lewis and Slater (1954) reported that 

 the phosphorylation (P : O) ratio was considerably lower in the sarco- 

 somes of younger than in those of older blow flies, Calliphora erythro- 

 cephala (Meigen), so that by the loth day this P : O, as well as the 

 P : alpha-ketoglutarate ratio, was twice as great as that of the young 

 imago. Furthermore, oxidation of alpha-ketoglutarate by such particles 

 isolated in versene was at least doubled by the addition of dinitro- 

 phenol (to an incubation mixture which included also glucose and 

 hexokinase) for flies i to 2 days of age; no such activation was pos- 

 sible for sarcosomes isolated from flies 9 days of age (Slater and 

 Lewis, 1954) . These isolated data represent fragments of a still poorly 

 understood pattern of metachemogenesis within the sarcosomes, which 

 may be eventually linked more precisely with the postemergence 

 maturation of dipteran flight muscle and of the function of flight itself. 



EVIDENCE FROM INSECT ENDOCRINOLOGY 



Shortly after the appearance of a preliminary treatment of this 

 subject of metachemogenesis as a cryptic, biochemical manifestation 

 of postemergence maturation in holometabolous insects (Rockstein, 

 1956), the writer received a communication containing several perti- 

 nent, stimulating observations from Dr. Berta Scharrer, one of our 

 leading endocrinologists, in which she volunteered additional instances 

 of postemergence maturation in the corpus allatum of such insects. 

 This organ has been the object of intensified study during the past 

 10 years as the gland that maintains the juvenile state by the secretion 

 of the "juvenile hormone" ; conversely, when this secretion ceases 

 "metamorphosis" takes place (Wiggles worth, 1954, p. 94) under the 

 stimulus of the prothoracic (or "thoracic") glands' growth and moult- 

 ing hormone; (after emergence of the adult the one recognized func- 

 tion of the corpus allatum has been the maturation of the ovaries). 

 Aside from controlling maturation of reproductive function, there is 

 some evidence that the histological changes reported as continuing 

 into adult life may be related to functions other than sexual matura- 

 tion. Thus, Day (1943) found a persistence of the larval fat body 



