General effects of increased and decreased pressures of oxygen on dove embryos

Abstract

Compared with hatched young or adults the dove embryo has very inferior powers of adjustment to either high or low oxygen pressures. The earliest stages, in fact, wholly lack the usual or other apparent mechanisms of respiratory compensation. Contrary to permissible inferences from the few studies hitherto made with older embryos only, it is found that the embryos in the youngest stage are usually much affected by prolonged high concentrations of oxygen. Some of these embryos are killed by subjection to high oxygen pressures during 24 hours; others may temporarily survive—as shown by heart-beat—for more than four days, but these embryos usually fail to develop blood pigment, become highly abnormal and remain of very small size; some of these abnormal embryos practically complete their development—producing “monsters” in which the head and eyes are most often affected. That such abnormal embryos and monsters arise only from very young embryos, of 2.2 days or less, is indicated by the data of Table I.

It should be stated that monsters rather similar to those induced by the increased oxygen have resulted also from treatment with reduced oxygen pressures and these have all been produced in embryos aged 2 days or less at the time of treatment. However, some of the abnormalities of the types mentioned above are practically absent in series of embryos treated with reduced oxygen. That the monsters are in fact induced by the altered oxygen pressures is adequately shown by our complete data. These data are the result of 80 experiments upon nearly 2,000 embryos of various but precisely known ages, with oxygen concentrations varying from 8.0 to 96.5 per cent., and with duration of treatment extended from 8 hours to 10 days.