. Comparative animal physiology. Physiology, Comparative; Physiology, Comparative. Respiration and Metaholism 231 In the earlier stages of embryonic development there appear abrupt changes in the respiratory exchange, correlated with profound developmental mile- stones as cleavage, gastrulation, diapause, metamorphosis, and fertilization itself. Years ago Warburg-*''" demonstrated a seven-fold increase in oxygen consumption in Arhacia eggs at the time of fertilization, a phenomenon ade- quately substantiated on a number of other forms. In Fundulus, besides the increase at fertilization, a
. Comparative animal physiology. Physiology, Comparative; Physiology, Comparative. Respiration and Metaholism 231 In the earlier stages of embryonic development there appear abrupt changes in the respiratory exchange, correlated with profound developmental mile- stones as cleavage, gastrulation, diapause, metamorphosis, and fertilization itself. Years ago Warburg-*''" demonstrated a seven-fold increase in oxygen consumption in Arhacia eggs at the time of fertilization, a phenomenon ade- quately substantiated on a number of other forms. In Fundulus, besides the increase at fertilization, a second marked increase occurs at about the time 200 10 -. 20 AGE 30 M Fig. 49. Decrease in metabolic rate with age of several birds and mammals. Age in months, except for man in years. After Benedict and ; when the vascular system begins to flourish. That all embryonic forms do not follow the same respiratory pattern, however, is clear from the work of Tang'^'^" on the starfish and that of Brachet"*^ on Amphibia, which show no increase in oxygen consumption at fertilization. In fact, the clam, Cwningia, and the annelid, Chaetoftenis, undergo a decrease in oxygen uptake at the time of fertilization.'*"-' â¢^"â ' An increasing metabolic rate of rat eggs during early cleavage is correlated with an increase in volume, in turn attributed to water uptake and probable yolk-protoplasmic conversion.'*" For an extensive review of the literature concerning embryonic metabolism, the reader is referred to the thorough treatment by Needham--^'-' and ^*^. 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 Prosser, C. Ladd (Clifford Ladd), 1907-; Bishop, David W. Philadelphia, Saunders
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