The fate of phosphorus ( P ) containing compounds during the metamorphosis of insects is of special interest in view of the importance of these materials in intermediary metabolism.It is probable that the majority of such compounds in insects are identical with those niore widely studied in other forms ; thus, the adenosine triphosphoric acid (ATP) isolated from Drosop7ziln by Albaum and Rletzkin ('48) and from locust muscle by Calaby ('51) is identical with the A T P of mammalian tissue. The ribose nucleic acid (RNA) of hlowfly larvae characterized by Rhoiivine and Gregoire ( '44) is identical with that of yeast. The insect phosphagen, argininc phosphate, has been found to be the same as in other invertebrates (Baldwin and Needham, ' 3 3 ) . Further, Hassett ('51) has shown that a number of phospliorylated sugars which are intermediates in the glycolytic cycle are rapidly utilized by cockroach tissues, indicating that these P-esters occur normally as components of carbohydrate metabolism.During adult development, marked changes occur in both the distribution and kind of P compounds present in insects.Heller ( '31) showed that the level of inorganic P in the blood of the diapausing hawk-moth (Deilephila euphorhine) pupa was inversely proportional to the U-shaped respiration curve. This work was later extended to include the distribution and arnomits of inorganic P, phosphagen P, easily acid labile I' (if!., 7 min. hydrolyzable P assumed to be ATI'), and total trichloroacetic acid (TCA) soluble P in the various tissues o € the larval, pupal and adult stages (Heller, '36; Heller, Swiechowska and Karpiali, '49). From these studies a correlation was dram-n between the concentration of easily hydrolyzable I' and the metabolic rate at the various stages of derelopment. The cliangcs in 4 types of P compounds were investigated during the metaniorphosis of C. erythroceyhaln by Khouvine and Gregoire ( ' S O ) ; they found that, expressed on a weight basis the total 1' remained constant during the wliolr~ of adult development, but quantitative changes occurred in the diffcrcrit P fractions. Their results will be discussed in greater detail below.I n the present work, the variation in P compounds during adult development of the blow-fly has been determined by methods more recently developed than those employed by Khouvine and Gregoire ('4O), permitting of a somewhat more definite characterization of these materials. Although the data to be presented a r e as yet incomplete, sufficient experiments h a r e been performed to warrant the drawing of certain conclusions, and to indicate the nature of the problems remaining to be solved.
MATERIALS AilSD METHODSThe C. erythrocephala pupae used in the present experiments were obtained from a culture which had been in-bred in this laboratory for many generations. Two days after the fully grown larvae had left the meat on which they had been raised, the culture was examined at intervals of about two hours, and those showing the first signs of "rounding u p " were picked out and ter...