PHYSIOLOGY OF THE SPERMATOZOON 117 



nated masses break up and reversal is completed; with 

 low concentrations, on the other hand, the agglutinated 

 masses are smaller and their disintegration is correspond- 

 ingly more rapid. It is therefore possible to establish 

 a unit concentration of the agglutinating substance 

 denned as the greatest dilution at which an unmistak- 

 able reaction is given. Such a reaction lasts only four 

 or five seconds, and the agglutinated masses are too 

 small to be seen with the unaided eye. Any given egg 

 water may therefore be rated by the amount of dilution 

 required for reduction to unit strength, as containing 

 10 or loo, or 6,400, etc., agglutinating units. The highest 

 concentration obtained in my experiments on Arbacia 

 was 12,800 units. Just (1919) has obtained an equally 

 high concentration in Echinarachnius egg water. 



c) Properties of the agglutinating substance. We 

 may now examine some of the properties of the agglu- 

 tinating substance: first, its biological properties; 

 second, its physical and chemical properties. 



Biological properties: Apart from the data already 

 considered we may note that the eggs alone produce 

 this substance; it is not contained in the blood (peri- 

 visceral fluid), even of mature females, or in extracts 

 of any other tissues. We thus have a specific relation 

 between egg and spermatozoon that does not obtain 

 between any other tissues and the spermatozoon. The 

 substance is tissue specific. 



It is produced by mature eggs alone and ceases to 

 be produced by fertilized eggs. Thus its production 

 period coincides exactly with the'fertilizable period of 

 the ovum. The greatest care has been taken to deter- 

 mine this point; no quantity of ovarian substance 



