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THE AMEBIC AN NATURALIST [Vol. XLIX 



ciscanus does not give a trace of agglutination with the 

 sperm of purpuratus but if the experiment is made in 

 m/2 NaCl solutions it can be shown that the franciscanus 

 egg NaCl solution activates the Nad sperm of pur- 

 puratus in an m/2 NaCl solution very strikingly. 



The immature eggs of Asterias ochrarca activate the 

 otherwise non-motile sperm of the same species, but the 

 eggs of this starfish do not give any agglutination reac- 

 tion with their own sperm and Lillie found the same for 

 the starfish in Woods Hole. It might be said that all this 

 only proves that the activating effect requires a smaller 

 concentration than the agglutinating effect, but may yet 

 be caused by the same substance. This objection is, how- 

 ever, not tenable in the following case. 



Purpuratus sperm washed in m/2 NaCl is as a rule 

 more active in a mixture of NaCl + KC1 than in a. mixture 

 of NaCl -j- CaCl 2 (if both solutions are free from egg con- 

 tents) ; yet in the latter solution the agglutination reac- 

 tion upon the addition of egg-NaCl is very strong while 

 in the former it is lacking (unless the sperm or testicles 

 or ovaries give off some CaCl 2 to the surrounding solu- 

 tion). Again it might be argued that the activation of 

 the spermatozoon might be induced by the same sub- 

 stance as the agglutination, but that the agglutinating sub- 

 stance in both cases reacted with different constituents 

 of the spermatozoon. While this may be admitted, it 

 must also be conceded that with the facts which we have 

 at our disposal at present we can not be certain that the 

 aggu It 'mating and activating substances are identical. 



VII 



Lillie 22 not only takes the identity of the two substances 

 for granted but lie assumes that without the agglutinating 

 substance in the egg (to which he gives the somewhat 



