CHAPTER 20 



Properties of egg fractions 



Egg fractions have been used to analyze the effect of ultraviolet light 

 and x-rays, etc. on the egg cell (see Part IV) ; quite a number of studies 

 have been made of the chemical and physical properties of the half-eggs 

 in order to evaluate the part which the various granular layers may play 

 in the life of the cell. Some of the results are given in condensed form 

 below. 



Consistency. - When manipulated with a needle the red halves are 

 found to be sticky and glutinous and can be pulled out in strands, 

 while the white halves explode if punctured (E. B. Harvey, 1932; see 

 Chambers, 1938 a). The fertilization membrane which forms on the 

 white half is much thinner than that on the red half. 



Density. - White half, 1.076; red half > i.i when obtained with 

 10,000 X g. Whole egg without jelly 1.084. (E- N. Harvey, 1932). 



Osmotic Behavior. - Closely parallels the whole egg. The value for 

 osmotically inert material b is twice as great in the red half as in the 

 white half, but computation of b magnifies experimental error and 

 the difference in white and red halves may not be as great (Lucke, 

 1932). Actual values for the volume change in hypo- and hypertonic 

 sea water are given in Table 12. Water enters white halves several 

 times more rapidly after fertilization than before (Shapiro, 1939 a). 



Electrical Properties. - The electrical capacity of the white half and 

 red half is the same as that of the whole egg, about i microfarad per 

 cm^. On fertilization, the capacity of whole eggs and white halves in- 

 creases 3-4 times (Cole and Curtis, 1938; Cole, 1941). The details are 

 given in Part IV. 



The internal resistance of whole eggs and white halves, fertilized 

 and unfertilized, is about the same, 180 ohms per cm^ but the internal 

 resistance of red halves (unfertilized) is 3 to 6 times that of the whole 

 egg (Cole and Curtis, 1938; Cole, 1941). The details are given in 

 Part IV. 



The surface charge (zeta potential) of whole eggs is — 30.8 ± 0.54 

 millivolts; white halves, — 20.9 ± 0.69 millivolts; red halves, — 27.6 

 zh 0.35 millivolts (Dan, 1936, IV). 



