H. M. FucHS 301 



animals which have been in the Aquarium fur one night or longer 

 decreases it. 



12. Egg-extracts of Phallusia, Arbacia and Strongylocentrotus and 

 egg-secretions of the two latter increase the fertilizing power of sperm- 

 suspensions of Giona. 



13. The fertilizing power of a Strongylocentrotus sperm-suspension 

 used to fertilize eggs of the same species, is increased to the same extent 

 by egg-e.xtracts of Strongt/locentrutus, Sphaerechinus, Echinus and Ciena. 

 The fertilizing power of an Echinus sperm-suspension used to fertilize 

 the eggs of that form is increased to an equal extent by the extracts of 

 both these forms. 



14. Asterias egg-extract completely inhibits the fertilizing power 

 of a Strongylocentrotus sperm-suspension. The egg-secretion of Asterias, 

 however, increases the fertilizing power of the latter to the same extent 

 as does Strongylocentrotus egg-secretion itself. 



15. A small rise in the H-ion concentration of the water gives an 

 increase in the fertilizing power of a sperm-suspension of Giona; while 

 a small fall causes a very marked decrease in the latter. 



16. Water containing Giona, egg-extract has a very slightly greater 

 concentration of H-ions than normal watei'. Asterias extract, however, 

 has a considerably greater concentration. The blood of Giona shows no 

 change in reaction con-elated with its changed effect on the fertilizing 

 power of sperm-suspensions. 



REFERENCES. 



1. Vox DuNGERN, E. "Neue Versuche zur PhysiologiederBefruohtung." Zeitschr. 



f. ally. Physiol. Bd. i. 1902, S. .34. 



2. LiLLiE, Frank R. "The production of sperm i.so-agglutinins by ova." Science, 



Vol. xxxvi. 1912, p. 527. 

 3. "Studies of Fertilization." V. /oura. E/;;^ .^oo^. Vol. xiv. 191.3, p. 515. 



4. SoRENSEN, 0. R. C. R. Lab. Carlsbery, Tom. viil. 1909, p. 1. Also Biochem. 

 Zeitschr. Bd. xxiv. 1910. 



