138 CARL RICHARD MOORE. 



Various workers in contributing to the analysis of the problem 

 of fertilization have presented many and diverse points of 

 attack. One method or group of methods that has produced 

 very striking results is that of initiation of development by 

 known chemical agents, largely developed through the excellent 

 works of Loeb in his studies on artificial parthenogenesis. 



Lillie ('13 and '14) has discovered and described a specific 

 sperm agglutinating substance secreted by the eggs of two 

 maiine forms (Arbacla punctulata and Nereis limbata). This 

 substance is produced by the eggs of these forms at the time 

 of rupture of the germinal vesicle and is liberated into the 

 sea water, in which eggs have been standing for a short while: it 

 escapes from the eggs in amounts readily detectable by using a 

 sperm suspension of the same species as an indicator. Sperm are 

 agglutinated in masses that break apart after a longer or shortei 

 time; the reaction is reversible. To this agglutinating substance 

 he has given the name fertilizin. 



The nature of this substance is very little known but a number 

 of its properties have been determined by Lillie and later Glaser 

 ('14) has offered certain information concerning it. Of inteiest 

 at present however is its r61e in the process of fertilization. 



Fertilizin according to Lillie is always present in eggs when 

 fertilization is possible, and so far experiments have shown it 

 present in quantities sufficiently large to be detected by its 

 sperm agglutinating properties. It is not detectable in imma- 

 ture eggs, likewise it is absent or bound immediately, or within 

 a very short time, following the act of fertilization. In these 

 two cases then there is a correlation between the presence of 

 fertilizin and the capacity for fertilization; indeed Lillie has 

 extended this conception to include all conditions of an egg- 

 when fertilization is possible fertilizin is present. He holds that 

 fertilization is a reaction or set of reactions in which this ovo- 

 genous substance fertilizin is activated: it is then "the effective 

 agent which is transformed from an inactive to an active state 

 by some substance in the spermatozoon." 



The fertilizhin ypothesis attempts also to explain the mechan- 

 ism of artificial parthenogenesis by assuming that development 

 in this case is effected or initiated in essentially the same manner, 



