. Chemical embryology. Embryology. SECT. 4] HEAT-PRODUCTION OF THE EMBRYO 661 reached its minimum at the time when the embryos were curved like a U, and it rose again during the main period of increase in length and the assumption of mobihty by the embryos. If, then, the Ascaris egg is burning its reserves completely to carbon dioxide and water, it could be stated roughly that a period of protein or mixed fat-protein combustion was succeeded by a period of carbohydrate or mixed protein-carbohydrate combustion. Later work by Brown shows that a difference of temperature has no influence on the a
. Chemical embryology. Embryology. SECT. 4] HEAT-PRODUCTION OF THE EMBRYO 661 reached its minimum at the time when the embryos were curved like a U, and it rose again during the main period of increase in length and the assumption of mobihty by the embryos. If, then, the Ascaris egg is burning its reserves completely to carbon dioxide and water, it could be stated roughly that a period of protein or mixed fat-protein combustion was succeeded by a period of carbohydrate or mixed protein-carbohydrate combustion. Later work by Brown shows that a difference of temperature has no influence on the amount of oxygen taken up by nematode eggs during their development, but only affects the rate at which this process occurs^. Zavadovski has found that also in the case of the nematode tg^ {Ascaris) cleavage is stopped by lack of oxygen or by certain c Hours Fig. 122. concentrations of potassium cyanide. He has brought forward evidence showing that this egg has two kinds of oxidation-processes, one group affected by potassium cyanide and the other not affected, and that cell-cleavage is associated with the former group. Reznicenko, like Zavadovski, has studied the effect of potassium cyanide (in large amounts) on the respiration of nematode eggs, but with paradoxical results. Lite & Whitney have made some observations on the respiration of rotifer eggs. These do not normally hatch for many weeks after they have been laid, but if they are laid without a shell or with only a very thin one they develop fast, and hatch in a comparatively 1 This was confirmed by McCoy for the eggs of the hookworm, Ankylostoma caninum. These are exactly the same size as Ascaris eggs and take up the same amount of oxygen from fertiHsation to hatching, aUhough their speed of development under the same con- ditions is 21 times as fast. High oxygen tensions inhibit development of hookworm Please note that these images are extracted from scanned page images that may have been digitall
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