SECT. l] 



PHYSICO-CHEMICAL SYSTEM 



255 



It is quite evident that there are not two modes on the line joining 

 the points, i.e. that there are not two types of eggs, but only one type. 

 Faure-Fremiet made very similar experiments, determining the gly- 

 cogen content of the eggs histo-colorimetrically with iodine solutions, 

 and there also the frequency polygon had but one mode (Fig. 15 (^)). 

 But this second case was based on an unsatisfactory method. In the 

 particular instance under investigation, neither mitochondria nor 



30 



20 



12 3^5 



30 

 20 



\5 



(«) 



J : 



<k 5 7 8 



ib) 

 Fig. 15- 



glycogen happens to be an entity which varies as between the two 

 kinds of eggs. Nevertheless, the plan of work was an interesting one, 

 and widely extended researches with it, using accurate chemical 

 methods, would be very desirable. 



1-5. The Shell of the Avian Egg 



Litde attention has been paid to the shell of the bird's egg from a 

 physiological point of view. The relevant analyses are given in 

 Table 9. There is some difference between the shells of different 



