. Chemical embryology. Embryology. SECT. 9] PROTEIN METABOLISM 1089 We can now examine again the part played by ammonia, urea and uric acid as excretory products. Another way of expressing the relationship leads to the result shown in Fig. 326. Here, assuming that the ammonia, urea and uric acid together make up the total excreted nitrogen (which is not quite true), the partition between them has been calculated as milligrams excreted by the embryo each day in per cent, of the total nitrogen excreted by the embryo each day. Between the 4th and 5th days, the uric acid only accounts for 9 per ce
. Chemical embryology. Embryology. SECT. 9] PROTEIN METABOLISM 1089 We can now examine again the part played by ammonia, urea and uric acid as excretory products. Another way of expressing the relationship leads to the result shown in Fig. 326. Here, assuming that the ammonia, urea and uric acid together make up the total excreted nitrogen (which is not quite true), the partition between them has been calculated as milligrams excreted by the embryo each day in per cent, of the total nitrogen excreted by the embryo each day. Between the 4th and 5th days, the uric acid only accounts for 9 per cent, of the total nitrogen, but so rapidly does the change occur that, between the 8th and 9th days, it accounts for as. ⢠c t " a > â o (Oi Fig. 326. much as 90-7 per cent. It has therefore practically reached its adult level, as is shown by the comparative standards to the right of the graph. The shaded parts at the bottom represent urea and the rest uric acid; they are figures taken from Meyer; von Knierem; Schimansky; Meissner, and Steudel & Kriwuscha. It is clear that in the first week of development the relationship of urea and ammonia to uric acid is altogether different from what holds in the adult, but that in the last two weeks of development the adult value is rigidly adhered to. These results throw light on the fact that the allantoic fluid in the chick passes from pH 7-2 to pH 6-0 in the last half of incubation, whereas, before the 9th day, it has been constant at about pH 7-2 (see Fig. 211).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Needham, Joseph, 1900-. New York: The MacMillan Co.
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