90 



Scientific Proceedings (48). 



65 (674) 



On the isolation of oocytase, the fertilizing and cytolyzing 

 substance in mammalian blood-sera. (Preliminary 

 report.) 



By T. BRAILSFORD ROBERTSON. 



[From the Rudolph Spreckels Physiological Laboratory of the 

 University of California.] 



It has been observed by Loeb that the eggs of sea-urchins 

 (Strongylocentrotus purpuratus) may be induced to form fertiliza- 

 tion-membranes by immersing them in mammalian blood-sera 

 which have been rendered isotonic with sea-water by the addition of 

 NaCl. Occasionally, if the serum be especially potent, simple im- 

 mersion of the eggs in the serum suffices to bring about this result, 

 but as a rule previous treatment of the eggs with a sensitizing agent 

 (SrCl 2 or CaCU) is required. Prolonged action of the serum upon 

 sensitized eggs results in the cytolysis of the eggs. Very potent 

 sera usually cause agglutination of the eggs as well, especially of 

 sensitized eggs. 



I have isolated from ox-serum a fraction which is extremely 

 potent in fertilizing, cytolyzing, and agglutinating sea-urchin eggs. 



To 860 c.c. of fresh, whipped, and centrifugalized ox-serum, 

 which had been rendered isotonic with sea-water by the addition 

 of zYzM NaCl solution, I added 400 c.c. of 7 per cent. BaCl 2 . A 

 thick cloud was produced. This mixture after standing for an 

 hour in a warm place until its temperature rose to 37 0 C. was 

 centrifugalized. The entire precipitate, consisting of BaCC>3, 

 BaS04, and the barium compound of the fertilizing agent and, 

 possibly, of other substances, settled in the form of a cake at the 

 bottom of the centrifuge-tubes. This precipitate was thoroughly 

 drained and then suspended several times in 2 per cent. BaCU 

 and re-centrifuged in order to free it from adherent serum. It 

 was then stirred up for an hour in 100 c.c. of JV/10 HQ and the 

 insoluble residue (probably barium sulphate) was centrifuged out. 

 To the clear fluid thus obtained were added 10 c.c. of 10 per cent. 

 Na2S0< in order to free it from barium. This mixture was allowed 

 to stand for some hours at 50 0 and then centrifuged. The clear 



