474 ALVALYN E. WOODWARD 



an oxidase reaction is given. It seems, therefore, that the oxi- 

 dase present within the egg cannot permeate the normal mem- 

 brane, and is not present in 'pure' fertilizin. 



That catalase is not present in the secretion unless the eggs 

 have been laked or cytolyzed is indicated by the fact that such 

 an extract does not free oxygen from hydrogen peroxide (method 

 of Loevenhart, '05). The eggs themselves, however, contain a 

 considerable amount of this enzyme, which, like the oxidase, 

 cannot permeate the normal membrane. This was also observed 

 by Amberg and Winternitz ('11). 



No evidence of the presence of a proteolytic enzj^me could be 

 demonstrated by the digestion of egg albumin by either fertilizin 

 or a precipitate obtained from the secretion. This, of course, 

 does not preclude the possibiUty of the presence of an enzyme 

 that splits some Arbacia protein, but is powerless against that of a 

 hen's egg. 



While it was not expected that the secretion would contain an 

 amylase, a mixture of fertilizin and boiled starch was allowed to 

 stand several hours. At the end of that time, Benedict's test 

 for sugar was applied with negative results. The experiment 

 was also performed with a precipitate obtained from the secretion 

 instead of fertilizin, but with negative results as before. 



The only enzyme test with positive results was that for a 

 lipase. In order to execute this test, a fatty substance was 

 extracted from a large quantity of Arbacia eggs which had been 

 freed from water as completely as possible by centrifuging and 

 pipetting. The fat in these eggs was extracted with two or 

 more volumes of ether. Later, this fatty extract, when shaken 

 w4th water, formed an emulsion in which the fat globules were 

 quite small. By measuring these in a hanging drop with a mi- 

 crometer eye-piece, their diameters were found to be constant 

 for three hours. Fresh egg secretion in which the lipase might 

 be presumed to be present had no measurable effect on the size 

 of the drops. It w^ould be a mistake to conclude, however, that 

 lipase is absent. By a modification of Robertson's method (p. 

 475) it is possible to throw down a precipitate from egg secre- 

 tion soluble in w^ater and capable of dissolving the oil. The 



