STUDIES OF FERTILIZATION 557 



from the agglutination effect. It is very difficult to form a 

 definite opinion as to the real nature of the agglutination effect. 



6. THERMO-RESISTANCE OF THE AGGLUTININ 



The agglutinating agent is slowly destroyed at 95°C. : 



August 28. Arbacia: (1) Ovaries and eggs of Arbacia were cut up in 

 three times their bulk of sea-water, and let stand about an hour. The 

 supernatant fluid is strongly agglutinative on Arbacia sperm suspensions, 

 (a) Part of it was now taken and boiled about thirt^^ seconds, and cooled. 

 On test it proved as agglutinative as before, (b) Some more was then 

 boiled five minutes and cooled. Its agglutinative power was apparently 

 undiminished, (c) Another egg-extract similar to the first was then 

 boiled and put in a beaker of boiling water for thirtj' minutes; the tem- 

 perature stood about 95° during this process. On test its agglutinative 

 power was sho"^Ti to be greatly diminished, (d) In a fourth test some 

 egg-extract was kept at 95° for sixty-six minutes. It still exhibited some 

 agglutinative power, which, however, was very slight as compared with 

 the control. The heated egg-extract exhil^ited a considerable change 

 of color from the yellowish red of the control to a much brighter red. 



Simultaneously with the loss in agglutinating power, it appeared 

 also to gain in aggregating power: Drops of the hieated and the 

 unheated egg-extract were injected into the same sperm extract 

 beneath a raised cover. The drop of the heated expanded its 

 sphere of influence shown by immigration of the sperm about 

 twice as rapidly as the unheated; this was tested several times; 

 so that it would appear that the aggregative and agglutinative 

 agents are probably distinct, and that the agglutinin inhibits 

 aggregation to a considerable extent. 



Nereis: The eggs of three females were inseminated in 9 cc. sea-water; 

 the supernatant fluid has a slight amberish-green color, and is strongly 

 agglutinative on Nereis sperm, (a) After keeping at 95° C. for ten 

 minutes its agglutinative power was much reduced, (b) After twenty- 

 two minutes at 95°C. the agglutinin was entirely destroyed. The color 

 was entirely destroyed also. 



Thus the agglutinating substances, whatever they may be, 

 are either volatile being gradually driven off by heating, or they 

 are slowly coagulated or disintegrated chemically by a temper- 

 ature of 95°C. The agglutinin of Nereis is either more volatile 

 or more labile than that of Arbacia. It is impossible to say defi- 

 nitely to what class of chemical substances these agglutinating 



