450 SUMMARY OF CURRENT RESEARCHES RELATING TO 



a process of sperm-agglutination or cluster-formation when a number of 

 rapidly-moving spermatozoa (of sea-urchins and certain Annelids) strike 

 one another. Perhaps there is agglutination of the spermatozoon to the 



egg. 



"According to Lillie, fertilization consists in the combination of the 

 spermatozoon with a molecule of " fertilizin "in the egg, whereby the 

 fertilizin molecule undergoes a change in the other end, and this change 

 causes the egg to develop. The fertilizin is thus an amboceptor in 

 the sense of Ehrlich's side-chain theory (Egg-Fertilizin-Spermatozoon). 

 Loeb criticizes this speculation. He holds that no adequate proof has 

 been offered thus far for the connexion between the power of an egg of 

 being fertilized by sperm, and its power of causing a cluster-formation 

 of the sperm. It is difficult to see why such a relation should exist, 

 since sperm-agglutination can only inhibit the entrance of the sperma- 

 tozoon into the egg. 



Relation of Spermatozoa to Electrolytes.* — James Gray calls 

 attention to the fact that ripe spermatozoa of Luidia, which remain 

 motionless in sea-water, are activated by the addition of a few drops of 



r- NaOH, and proceed to fertilize the eggs. The spermatozoa do not 



move in acid sea-water. The cessation of movement is due to the 

 absence of hydroxyl-ion in the surrounding medium. By increasing the 

 alkalinity movement is induced. Cessation of movement in too alkaline 

 sea-water causes agglutination, and this cannot be reversed by adding 

 acid. The fact that the effect of acid can be removed by the addition 

 of alkali suggests the possibility that the movement of spermatozoa is 

 dependent upon the electromotive properties of the cell and its medium. 



When an electric current is passed through a neutral suspension of 

 spermatozoa in cane-sugar, the sperm travels rapidly to the positive pole, 

 where it accumulates (as Lillie observed in the case of the frog) ; round 

 the negative pole, however, the spermatozoa become exceedingly active, 

 which is due to the liberation of alkali. In a faintly acid solution of 

 cane-sugar, no migration occurs to the positive pole, and no activation 

 at the negative pole. The spermatozoa form a retiform aggregation 

 throughout the solution. It is concluded that motile spermatozoa 

 possess a negative charge on their surface, and that this charge is lost 

 in the presence of free hydrogen ions. 



If a drop or two of very weak solution of cerous chloride is added to 

 a suspension of Arbacia sperm, the spermatozoa become intensely active 

 and form active clumps. Experiments with neodymium nitrate gave 

 similar results. As the effect of these trivalent positive ions is removed 

 by means of sodium nitrate, it is suggested that the trivalent ions affect 

 the spermatozoa by virtue of their electrical charge. 



Lillie found that sea-water which had been in contact with unferti- 

 lized eggs and extracted " agglutin " from them had a marked effect on 

 spermatozoa, greatly increasing their activity, aggregating them, and 

 agglutinatine; them. 



L *&p J 



* Quart. Journ. Micr. Sci., lxi. (1915) pp. 119-26. 



