SECT. 5] 



IN ONTOGENESIS 



789 



various solutions. This is the ontogenetic history of the water relations 

 of tadpoles." Adolph pointed out, with reference to the increasing 

 water regulation apparent from the results of Backmann and his 

 collaborators, that the most important factor was probably the em- 

 bryonic ectoderm, for there is no evidence that the egg-membranes 



c 



Age 

 Change of volume in o-o8 M NaCl related to age 



Fig. 182. The development of the power of regulating 

 body-volume in Rana pipiens. 



play any part in regulating the distribution of water between the 

 body of the embryo and the environment of the egg. 



Belehradek & Huxley subsequently found that the water-regulating 

 power of Amblystoma ; imperfect during the larval state, assumes its 

 adult efficiency during metamorphosis. Konopacki's conclusions are 

 also in general agreement with those of Adolph. He studied the 

 effects of distilled water on amphibian eggs and embryos, and showed 

 the coming-into-being of a regulatory mechanism, probably resident 

 in the embryonic ectoderm. Konopacki also confirmed many of 

 Bialascewicz's results with reference to the function of the peri- 

 vitelline liquid in the frog's egg. 



