86o 



GENERAL METABOLISM 



[PT. Ill 



Fig. 213. 



Striking because their yolk figures also rise parallel with the earlier 

 ones, only again one pH unit higher. All these relations are shown 

 in Fig. 211. The cross-over 

 between yolk and white occurs 

 at almost the same place in 

 all cases. 



Buytendijk & Woerde- 

 mann's figures, given in 

 Fig. 211, show a good agree- 

 ment with the results of the 

 previous observers, which is 

 rather gratifying in view of the 

 good technique used by them. 

 A point of much interest is 

 that Buytendijk & Woerde- 

 mann measured the pH of the 

 less viscous and the more vis- 

 cous parts of the white separ- 

 ately, and found that, while 

 the pB. of the white as a whole was falling, that of the former part of 

 it fell more rapidly than that of the latter part. Doubtless this is due 

 to the faster diffusion of the responsible acids into the more Hquid 

 portions. The electrometric 

 work of Gueylard & Portier 

 has also supplied a few figures 

 for yolk, white and amniotic 

 fluid, which have been in- 

 corporated in Fig. 211. Per- 

 haps they indicate a late acidi- 

 fication of the allantoic as well 

 as the amniotic fluid. 



Pigorini's figures for total 

 acidity of the silkworm egg 

 may be mentioned here (see 

 Fig. 213). 



We may now pass to the measurement of the pH of the embryonic 

 cells. For a time it was thought that results of value could be obtained 

 by crushing the tissues in some convenient apparatus, and then 

 estimating the pH of the "Pressaft" colorimetrically or electro- 



Fig. 214. 



