886 GENERAL METABOLISM [pt. iii 



put into distilled water. Here, however, it must be remembered 

 that the embryo cannot be separated from the yolk-sac, so it is the 

 water-content of embryo plus yolk that is being measured. And where 

 the yolk is allowed for, as in v. Bezold's work on Bombinator igneus, 

 the water-content follows the usual rule and decreases, thus : 



On the other hand in the case of fish eggs it is possible to separate 

 the embryo from the yolk from a comparatively early period onwards, 

 and for the trout, where this has been done, the water-content of 

 the embryonic body does not seem to change at all. Fig. 232, con- 

 structed from the figures of Kronfeld & Scheminzki and of Gray 

 shows this very definitely, and it would seem that the water-content 

 of the trout embryo never varies much from 85 per cent, though, of 

 course, it may be higher in the earlier period which was not 

 investigated. From the work of Faure-Fremiet on the egg of 

 Sabellaria alveolata it is not possible to learn much, for the yolk was 

 never separated from the embryo, and we cannot say therefore what 

 was the significance of the loss of 5 per cent, in dry weight. Teissier's 

 study of the development of the medusa Chrysaora hyoscella, how- 

 ever, demonstrated that, although the adult medusae have a great 

 deal of water in their bodies, the early stages have much less. 

 Thus he obtained the following results : 



Table 103. 



Organic Phos- 



Ash substance phorus 



2-3 31-4 0-33 



3-2 25-8 0-27 



But it might perhaps reasonably be argued that the water-content 

 of medusae is so unusual that the ordinary relations would not be 

 expected. Histological arguments supported the view that, while 

 the early increase in water-content was due to intracellular swelling, 

 the later increase was intercellular, due to the mesoglia. 



