878 



GENERAL METABOLISM 



[PT. Ill 



was high in the embryonic body. Too high humidity gave, he found, 

 a worse mortahty than too low. 



We have seen, then, that the egg as a whole is continually losing 

 water at a constant rate, and that the embryo is continually gaining 

 it at an ever-decreasing rate, so that it becomes less and less wet 

 as it develops. The third cardinal fact in the water metabolism of 

 the hen's, egg is that the yolk is gaining water at the expense of the 

 white. This process has already been alluded to in the Section on 



Waber-content of Yolk &, White 

 Whibe Yolk 

 O • Bellini 

 n ■ Vladimirov 

 O ♦ Agga35otbi 

 A lljin 



y Barbelme5 &, Riddle 

 ^ Tang] 

 4 Prevosb&MorIn 



Komori 

 > Riddle 



Emrys - Roberbs 



10 15 20 



Fig. 225. 



biophysical phenomena, where the viscosity and the osmotic pressure 

 of the yolk and the white necessitated its mention. There is reason, 

 in fact, for believing that the yolk absorbs water from the white 

 from the moment at which they first come into contact, i.e. in the 

 oviduct, but it is probable that the mechanism by which this is done 

 differs as time elapses, and as the embryo grows. The actual deter- 

 minations of the water-content of yolk and white are assembled in 

 Fig. 225, from which it can be seen that the results of all investigators 

 from Prevost & Morin onwards agree well together. A little un- 

 certainty, however, exists with regard to the course taken by the 

 yolk after the mid-point of development, for Bellini's figures would 



