Ii8 



Scientific Proceedings (52). 



contained appreciable traces of phosphates. I have obtained a 

 much purer preparation by a process consisting, essentially, in 

 precipitation from the serum by acetone, extraction of the precipi- 

 tate with hot N/10 HC1, exactly neutralizing the extract with 

 Ba(OH) 2 , re-dissolving the precipitate in N/10 H2SO4 and re- 

 precipitating it with acetone. The yield from a liter of ox-serum 

 lies between 10 and 40 milligrams. 



The substance which is thus obtained is soluble in dilute acids, 

 alkalies and salt-solutions. It is much more rapidly dissolved 

 when these solvents are hot. Its solutions are not coagulated 

 by boiling. It is thrown out of solution by chlorides of the alkaline 

 earths. It yields the Millon, Acree-Rosenheim and xanthoproteic 

 tests for protein. One part of the substance rubbed up in 512,000 

 parts of sea-water caused membrane-formation in 80 per cent, of 

 Strongylocentrotus purpuratus eggs which had previously been 

 sensitized by 4 minute's immersion in 3/8 m SrClo. 



The active substance, therefore, is either a protein or a peptone, 

 or else, by the above methods of preparation, is precipitated to- 

 gether with a protein or peptone. 



I find that Witte's "peptone" contains the membrane-forming 

 substance, since one part of Witte's "peptone" dissolved in 

 16,000 parts of sea-water caused membrane-formation in 32 per 

 cent, of sensitized purpuratus eggs. Hence the membrane-form- 

 agent is digested either with difficulty or not at all by pepsin. 



I find that the addition of 0.08 per cent, of lecithin or cholesterin 

 to rabbit serum does not affect, either qualitatively or quantita- 

 tively, the membrane-forming and cytolyzing action of the serum. 

 It would appear very unlikely, therefore, that the active substance 

 is a lipoid. 



78 (774) 



On the influence of lecithin upon the development of sea-urchin 

 embryos. (Preliminary communication.) 

 By T. Brailsford Robertson. 



[From the Rudolph Spreckels Physiological Laboratory of the Uni- 

 versity of California.] 



When the eggs of Strongylocentrotus purpuratus are fertilized 

 by sperm in a mixture of 50 c.c. of sea-water and 5 c.c. of a 1.7 



