. Chemical embryology. Embryology. 910 GENERAL METABOLISM [PT. Ill. Hatching Fig. 243. absorbed by the larvae, though the time they took to absorb a definite amount was, of course, made longer or shorter. The effect of rising temperature on the unfertilised eggs was to increase the permeability of their membranes to water, so that, for instance, at 10°, an egg in a definite period would increase its volume by 0-05 , and at 20° by 0-28 But the possibihty that the increase with temperature was really due to the production of an unusually large amount of osmotically active substances i
. Chemical embryology. Embryology. 910 GENERAL METABOLISM [PT. Ill. Hatching Fig. 243. absorbed by the larvae, though the time they took to absorb a definite amount was, of course, made longer or shorter. The effect of rising temperature on the unfertilised eggs was to increase the permeability of their membranes to water, so that, for instance, at 10°, an egg in a definite period would increase its volume by 0-05 , and at 20° by 0-28 But the possibihty that the increase with temperature was really due to the production of an unusually large amount of osmotically active substances in the egg-protoplasm was not ex- cluded. Bialascewicz argued that as the permeability to water is increased five times by a rise of temperature of 10°, and as the development rate is increased only two and a half times, one would expect to find more water in larvae brought up at 20° than at 10°. Since experimentally this was not the case, Bialascewicz concluded that the permeability of the membranes to water was not the determining factor in the absorption of water during amphibian embryonic growth. Galloway, inspired by Davenport's early work, also made a study of the effect of temperature upon the absorption of water by the developing frog larva. The embryos of Rana sylvestris, Amblystoma punctatum and Bufo americana were subjected to temperatures varying from 6° to 25°, and the water-content estimated from time to time. The results obtained are shown plotted in Fig. 243, whence it can readily be seen that the warmer the environment, the more rapidly did the imbibition of water go on. But Galloway found that at higher temperatures the final amount of water in the body was slightly more than that at lower temperatures although the develop- mental process up to the point when 75 per cent, water was reached was not so much retarded by lower temperature as the stage representing the maximum percentage of water. (See Table 107.) The effects of temperature, therefore, were m
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