20 FRANK R. LILLIE. 



tion ; evidently because the physical change on which the reaction 

 depends is not sufficient to cause adhesion except when the 

 spermatozoa positively collide.^ These six criteria definitely 

 define the phenomenon. 



Agglutination is positively distinct from aggregation. It is 

 an entirely different biological phenomenon. The two may, 

 however, be exhibited simultaneously, as when a drop of egg 

 secretion of Arhacia is injected into a sperm suspension of the 

 species. In such a case the spermatozoa exhibit positive chemo- 

 taxis to one constituent of the egg secretion, and are agglutinated 

 by another (the fertilizin). The separateness of these two sub- 

 stances was maintained in my first publication on the subject and 

 demonstrated by repeated experiments (see Lillie, 1913a, p. 549, 

 and 1 9 14, pp. 545-546). 



(4) The phenomenon of mass-coagulation is, on the other hand, 

 a lethal irreversible phenomenon. It may be exhibited in response 

 to various agents, such as KOH, NaOH, salts of lanthanum and 

 cerium,^ etc., and in some cases the secretions of the eggs of other 

 species or their blood. Hitherto I have not adequately defined 

 this phenomenon as distinct from the agglutination phenomena, 

 though in my last study (1914), I noted the distinction (p. 541). 

 The phenomenon is essentially lethal, but not all destructive 

 agents exhibit it; thus acids, so far as I have observed, destroy 

 the spermatozoa without causing mass coagulation. The 

 phenomenon is irreversible, and this suffices to distinguish it 

 froni true agglutination, even if no other criterion were available. 

 However, it exhibits quite a different aspect from agglutination; 

 in the latter the sperm masses tend to take on a spherical form; 

 if originally elongated they contract into balls or break up into 

 smaller masses which become spherical, thus offering considerable 

 resemblance to a phenomenon of surface tension, as Loeb notes. 

 The peripheral spermatozoa are in violent movement until the 

 time of reversal. In the mass-coagulation reaction, on the other 

 hand, there is no such surface tension effect, strands anastomose 



1 Loeb argues that the necessity of movement on the part of the spermatozoa 

 for the appearance of this phenomenon removes it from the category of true agglu- 

 tination; but this seems to me to be a purely arbitrary criterion. 



2 My attention was called to the action of the salts of these metals by a letter 

 from James Gray of Cambridge University. 



