434 



L. V. HEILBRUNN 



TABLE 12 



Eighteen-second tests. Eggs fertilized at 11. 4-0 a.m. Temperature at 11.42 a.m. 



U-3°; at 12.30 a.m., 2^.0° 



The tables show that the viscosity of the protoplasm under- 

 goes marked changes. With the same centrifugal speed some- 

 times two seconds are sufficient to produce zones, sometimes 

 sixteen seconds must elapse before zones appear. In the latter 

 case obviously the velocit}^ of the granules is only one-eighth 

 as great. Since the viscosity varies inversely as the velocity (see 

 previous discussion) this indicates an eight-fold increase in viscos- 

 ity. The number of seconds necessary to cause the appearance 

 of zones is thus an inverse measure of the velocity of granular 



