SECT. 5] 



IN ONTOGENESIS 



835 



and female nuclei, and falls when that process is complete. It rises 

 again to the diaster stage, and diminishes markedly immediately 

 before cleavage. The second augmentation would correspond with the 

 semipermeable phase of Herlant and the period of augmentation of 



20° 25"" 30° 35° 40° 



1-085\ 

 l-080; 



2-5 

 1-4 



Degree of / o-04 

 oblateness 



Specific 

 gravity 



Electric 

 charge 



% Eggs with 

 membranes 



Fig. 206. 



refractive index found by Vies. The curves with which this paper is 

 illustrated seem to indicate an unwarranted confidence in the ac- 

 curacy of individual points, and the number of observations is hardly 

 sufficient to establish some of the conclusions. 



The subject of protoplasmic viscosity has attracted a very great 

 number of investigators, and cannot be reviewed here, but certain 

 work of special embryological importance must be mentioned. In 



