ULTRAVIOLET AND ARBACIA FERTILIZATION. 



417 



Variations in technique will be noted as the various groups of 

 experiments are described. The following topics are considered ; 

 radiation of unfertilized eggs, " egg-water," sperm suspensions, 

 and agglutinated sperm ; adsorption of the colloidal components of 

 egg-water, and their partial recovery by HC1. 



A. Experiments u'itJi Unfertilised Eggs. Unfertilized eggs 

 were radiated " dry," for varying periods of time (15 sec. to 20 

 min.) and tested for fertilizin production, as follows; equal vol- 

 umes of sea-water (5-10 cc.) were added to equal quantities of 

 eggs immediately after radiation and allowed to stand for from 

 15 min. to 2 hr. The water was then decanted off, and its ag- 

 glutinating power measured. This was repeated from I to 5 

 times. The agglutinating power of a given sample of egg-water 

 was measured by successively diluting the sample until it no 

 longer gave a characteristic normal agglutinating reaction with a 

 i per cent, sperm suspension. The last effective dilution is an 



TABLE I. 

 ULTRAVIOLET RADIATION AND FERTILIZIN PRODUCTION. 



A. U. Agglutinating units. Tests were made against a I per cent, sperm 

 suspension. 



