METACHEMOGENESIS IN INSECTS — ROCKSTEIN 275 



INTRACELLULAR LOCALIZATION OF METACHEMOGENESIS 



With the appearance of the important work of Watanabe and Wil- 

 liams (1951), the identity of the interfibrillar sarcosomes from the 

 flight muscles of Diptera and Hymenoptera was established as organ- 

 ized units of respiratory metabolism, giant mitochondria. Later, 



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01 234 56789 

 AGE- DAYS 



Fig. 8. — Changes in cytochrome oxidase activity with age of female fiies. 

 (• resistant strain; ° normal strain.) (After Sacktor, 1950.) 



Levenbook and Williams (1956) found that the mean diameter of 

 such sarcosomes in the flight muscles of Phormia regina (Meigen) 

 rapidly increases from i to 2.5 micra during the first 7 days of adult 

 life, without any change in mitochondrial number. Concomitantly, the 

 dry weight follows this pattern exactly to reach a value three times 

 higher by the sixth day of imaginal life (fig. 10), just as the cyto- 

 chrome c titer increases to more than threefold during the same period 



