FERTILIZATION AND EGG-SECRETIONS. 69 



remain unsettled. An enzymatic effect is not demonstrated by 

 hydrolysis, but by acceleration in the rate of hydrolysis. 



Here again I cannot describe in detail the experiments which 

 I have carried out during the last two years. However I am able 

 to state very positively that the hydrolysis of neutral fats such 

 as olive oil and whale oil as well as the cleavage of lower esters, 

 such as ethyl butyrate are in fact accelerated not only by isolated 

 lipolysin, but also by freshly prepared egg-secretions. The 

 evidence, based on arbacia secretion, is given in the curves of 

 Fig. i. According to this lipolysin is correctly named for it is 

 in fact a lipolytic ferment. 



IV. 



Can we come to similarly close quarters with the agglutinin? 

 So far we have referred chiefly to the observable agglutination 

 reaction. This, as Lillie found, is accompanied by other visible 

 details. The agglutination of the spermatozoa is head-on. In 

 Nereis, where the spermatozoa are larger than among the 

 echinoderms, Lillie has described an actual swelling of the sperm- 

 heads associated with a loss of normal refrangibility. He has 

 suggested an increase of stickiness as the mechanism of agglutina- 

 tion. 



The adhesiveness of cells unquestionably depends on surface 

 properties and the effects of egg-exudates in general appear to be 

 favorable to the view that agglutination is related to an in- 

 complete superficial cytolysis of some sort. Aside from Lillie's 

 evidence, which is susceptible to this interpretation, I have 

 described a temporary agglutination of Arenicola larvae accom- 

 panied by an outflow of pigment. Furthermore, isolated agglu- 

 tinin has a marked effect on the surface of the egg. This quickly 

 develops a clear zone immediately under the membrane -a result 

 not only suggestive of membrane elevation but at the proper 

 stage, quantitatively, perhaps the essence of this much debated 

 process. 



Richards and Miss Woodward, in their experiments with 

 radiated egg-secretion, found evidence which suggests that very 

 possibly the agglutinin also, is an enzyme. At any rate, radia- 

 tion has opposite effects. If the secretion is radiated for two 



