Centimeters 



Figure 313. — Sperm suspension of C. virginica on a slide 

 in sea water (left) and in sea water containing a small 

 quantity of egg water (right). Drawn from life. 

 Natural size. 



Agglutination also occurs in the sperm of C. 

 gigas and in 0. circumpicta Pilsbry. Terao (1927) 

 experimented with the latter species using egg 

 water made by mixing 0.55 ml. of ripe eggs in 9 ml. 

 of sea water and removing the eggs by centrifug- 

 ing and filtering after they had stood for 20 

 minutes. The filtrate caused the isoagglutination 

 of sperm even in a dilution of 1 to 10 millions. 



Heteroagglutination 



by the 



water of 0. 



circumpicta has been observed in the suspensions 

 of sperm of the bivalve Area, sea urchin Toxo- 

 cidaris tuberculatus, and starfish Luidia quinaria. 

 LUlie (1919) regarded the sperm agglutinating 

 factor he discovered in Arbacia eggs as an essential 

 to fertilization, and to the active substance of egg 

 water he gave the name fertilizin. Tyler (1948) 

 identified fertilizin with the jelly substance of the 

 egg and on the basis of experimental data con- 

 cluded that the presence of the jelly coat has a 

 favorable effect on fertilization. B_v biochemical 

 analysis of sea urchin eggs, Vasseur (194Sa, 1948b) 

 determined the composition of the jelly coat and 

 found that 80 percent of it consists of polysac- 

 charide and 20 percent of amino acids. The sub- 

 stance was found to exert a heparinlike action in a 

 blood-clotting system (Immers and Vasseur, 1949). 

 After removing the jelly coat with acidified water, 

 Hagstrom (1956a, 1956b, 1956c, 1956d) found 

 that the rate of fertilization was higher than in the 

 presence of the coat. It is, therefore, apparent 

 that the jelly coat is not essential for fertilization. 



° Microns ^^ if. 



Fjgube 314. — Photomicrograph of sperm of C. virginica agglutinated by egg water of the same species. Phase contrast 



oil immersion. 



340 



FISH AND WILDLIFE SERVICE 



