476 ALVALYN E. WOODWARD 



of 7 per cent BaCL were kept at 37°C. for an hour or more and 

 stirred frequently. The mixture was then centrifuged and the 

 filtrate discarded. The precipitate was washed several times with 

 BaCL and then treated with N/10 HCl. To this solution was 

 added Na2S04 in excess to precipitate the barium, and the mix- 

 ture was allowed to stand overnight. The liquid was then cen- 

 trifuged and to the clear fluid were added four to five volumes of 

 acetone, which caused a heavy flocculent precipitate. This was 

 filtered, and the precipitate was washed several times with abso- 

 lute alcohoP and ether, and then dried for thirty-six hours or more 

 over H2SO4. The resulting powder dissolves readily in both sea- 

 water and distilled water. It should be added that this precipi- 

 tate was invariably obtained with good fertilizin and freshly 

 distilled acetone during the summer of 1915 and until about 

 the middle of July, 1916. It was never obtained by adding 

 acetone to sea-water. By the middle of 1916, all of the recently 

 purchased acetone had been used up, and recourse was necessary 

 to some purchased from Kahlbaum in 1912. This was yellowish 

 in color, slightly acid to litmus, and differed slightly in odor from 

 the fresh. With this acetone, no precipitate was obtained ex- 

 cepting after adding NaOH, and even then only in traces. 



Since (p. 474) the precipitate dissolves a fat extracted from 

 the egg, we may call its active principle 4ipolysin.' In solution 

 it does not agglutinate Arbacia sperm. It is, however, a very 

 efficient parthenogenetic agent (table 5). 



The solution used in these experiments contained about j cc. 

 of loose powder (about 0.025 grams) to 10 cc. sea-water. A 

 much larger percentage of normal larvae was obtained by this 

 precipitate than I have ever been able to obtain by any other 

 artificial method. 



It should be noted in this connection that, while the lipolysin 

 can be precipitated from mature Asterias eggs, it has been im- 

 possible to obtain any acetone precipitate from immature ones. 

 About 100 cc. each of A, immature, resistant starfish eggs and of 



2 The failure to obtain a precipitate with alcohol (p. 471) was due to its dilu- 

 tion. While this precipitate is insoluble ia absolute alcohol, it dissolves readily 

 in 75 per cent. 



