484 ALVALYN E. WOODWARD 



6. Unclassified inhibitors. Echinochrome, the red pigment 

 coloring Arbacia 'blood cells,' completely inhibits the cleavage 

 of Arbacia eggs. It is prepared by allowing Arbacia 'blood' to 

 clot, washing the clot with sea-water to rid it of serum, and then 

 laking the cells by adding a measured volume of distilled water. 

 To make this solution isotonic with the eggs, it is necessary to 

 add an equal volume of 'double sea-water,' i.e., sea-water boiled 

 down to one-half its original volume. 



It was suspected at one time that ' purple x' and echinochrome 

 might be identical. MacMunn ('85) found that the addition of 

 NaOH to echinochrome turned it yellowish, while HCl produced 

 a red-yellow color. Since neither reagent produces a color change 

 in 'purple x' (Woodward, '15), the suspicion has no foundation. 



We may summarize the methods of inhibition as follows: 



Foreign sperm (Godlewski, Herlant).. .Which occupy sperm recepto'rs (Lillie). 



Anti-fertilizin (Lillie) Which occupies the spermophile group 



(Lillie) and combines with lipolysin 

 (Woodward). 



Washing (Lillie) Which removes 'fertilizin' (Lillie). 



Blood of same species (Lillie) Which occupies ovophile group (Lillie). 



'Purple x' (Glaser) Which occupies egg receptor (Glaser) 



or causes physicochemical change in 

 egg (Woodward). 



* Salmon x' (Glaser) Ditto. 



Blood of related species (Woodward). .Which may combine with lipolysin (Wood- 

 ward) 



Fatty extract from eggs (Woodward). . .Which combines with lipolysin (Wood- 

 ward). 



Echinochrome (Woodward) Which appears to change egg itself 



(Woodward). 



IIL CONCERNING ACTIVATORS— PARTICULARLY LIPOLYSIN— AND 

 THEORIES OF ACTIVATION 



To the eye, 'activation' of an egg is manifested by cleavage. 

 Side by side with this goes an acceleration of metabolism indi- 

 cated by a three- to five-fold increase in the rate of oxidation in 

 developing over resting eggs (Warburg, '08 and Loeb and Was- 

 teneys, '13). This increased metabolism is also found in cyto- 

 lyzing eggs. 



