Abstract
In continuing our work on physiological ontogeny we have thought it of value to study the variation with time of the hydrogen ion concentration of the blood of chicken embryos. Estimates were made on embryos from 7 days of age to term. In making the measurements we used glass electrodes. We have taken precautions on the score of injury, the changes which take place during the process of dying, glycolysis and of temperature, the measurements being carried out in a warm room between 38 and 39° C. The usual precautions in the handling of blood have also been taken.
We find that at 7 to 8 days the blood is, relatively speaking, acid, and from 9 to 15 days maintains a rather level course somewhat more alkaline. At about the 16th day, the blood becomes still more alkaline and approaches the value found in adult chickens. We have studied both arterial and venous blood and mean to report upon these experiments in detail at a later time.
We have also taken blood from the foetuses of cats. From these we obtained figures indicating the presence of the same order of acidity. The data seem to indicate that the values are characteristic of embryonic growth in general and are not peculiar to the method of development, that is to say, of eggs versus foetuses.
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