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There is considerable evidence for the presence of both nucleic acids and proteins in the salivary gland chromosomes of certain diptera. The socalled "euchromatic" bands stain intensely after application of the Feulgen-Rossenbeck technique, which is a fairly specific test for the pentose of animal nucleic acids. The heterochromatic regions also give a weak reaction, and the boundaries between the bands are not sharp.' Caspersson2 found that the material of the euchromatic bands had a similar ultraviolet absorption spectrum to the nitrogenous bases characteristic of nucleic acids. There is little doubt, therefore, that the euchromatic bands are regions of high nucleic acid concentration. The presence of proteins in the chromosomes has been demonstrated by Caspersson, who found that the heterochromatic bands could be digested by trypsin, the euchromatic bands also being visibly affected. The results of Barigozzi,3 who stained salivary gland chromosomes of Chironomus with Millon's reagent, indicated the presence of protein along the chromosome, but this author found it impossible to observe much detail in his prepara

A'cw Por7; C i t y THREE FIGURESThe utilization of glycogen by the amphibian embryo has been in the past a subject of repeated experimental attack. Particular attention has been given t o glycogen utilization by the gastrula, for it was hoped that some correlation might be drawn between carbohydrate combustion and the phenomenon of induction. A brief survey of the literature will indicate however that doubts must attach to experiments purporting to prove regional differences in glycolysis of the gastrula. Crucial experiments morever are lacking whose specific objective was to test the relation between glycogen utilization and the various concomitant events which comprise the gastrulation process.Early studies of glycogen in the amphibian embryo depended on a qualitative, non-specific color reaction with Lugol's solution. Woerdcman ('33a), using such a test on urodele gastrulae, found at the dorsal lip of the blastopore a distinct boundary between uninvaginated presumptive chorda-mesoderm, rich in granules that stained brown with iodine, and invaginated dorsal lip material, almost entirely free of such glycogen granules.' Raven ( '33, '35) published histochemical results suggesting that the disappearance of glycogen from invagnating cells is not an autonomous event, nor a result of the new environment into which invagination carries the cells, but rather is dependent upon the "Einrollung" process itself. The observations of Woerdeman and Raven were qualitative, and had to be accepted with reservations that bear upon any histocheniical test which may be influenced by subjective errors in estimating comparative intensities of color. Pasteels ( '36) furthermore attributed the apparent glycolysis to faulty methods of fixation.Whether this embryonic glycogen is actually contained in granules, or whether it is of the submicroscopic " p r t i r n l a t e " type described for liver cells by Lazarow ('42) and in aphids (Loring and Pierce, '43), does not affect the significance of Woerdeman's findings. Since however iodine solutions coagulate proteins (Lazarow, '42) the granular appearance of glycogen hi these histochemical tests mag have been an artefact. 97

Several proteins extractable from frog's eggs in early stages of development are able to split inorganic phosphate from adenosine-tri-phosphate (ATP) (Barth and Jaeger, '47). The egg also contains a phosphoproteiri phosphatase (PPPase) and an endogenous substrate for this enzyme, as demonstrated first by Harris ('46) and later by Peinsteiii arid Yolk ('49). Harris suggested that the PPPase liberates phosphate from the stored phosphoprotein of yolk to meet the metabolic needs of the developing embryo. Our interest in ATPases as based on the hypothesis that such enzymes might function in the transfer of energy to proteinr significant for differentiation.Extracts made in dilute KC1 o r 10% NaCl at plI 6.8 contain both the ATPase and the phosphoprotein phosphatase (PPPase). The pH at which these enzyme mixtures are incubated, however, has a profound effect on the aniourit of inorganic phosphate measurable at the end of a given interval. The PPPase has a pHactivity range of pH 3.0-6.8, with a iiiaximum at pH 5.0, whereas ATPase activity can be dernonstrntd in the alkaline range from pH 6.8-9.2 where the PPPase is inactive. That the ATPase may be active also in the acid range Aided by a grant froill The Committee on Growth acting for The Amerlcaii Cnriccr Society arid a grant from The Rockefeller Fomlclation. 413

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