no Artificial Parthenogenesis 



Thus in 1901 Loeb^ and Neilson showed that a short 

 treatment with HCl and HNO3 sufficed to cause some 

 eggs of Asterias in Woods Hole to develop into larvae 

 without a second treatment being needed, and Delage^ 

 showed the same for CO/, and in 1905 the writer found 

 that the eggs of the Calif ornian starfish Asterina can 

 be induced to form a membrane by butyric acid treat- 

 ment and that ten per cent, of these eggs developed 

 into normal larvae. Quite recently R. S. Lillie ob- 

 served that the eggs of Asterias at Woods Hole can be 

 caused to form membranes and develop into larvae by 

 a treatment with butyric acid and that the time of ex- 

 posure required to get a maximal number of larvag varies 

 approximately inversely with the concentration of the 

 acid, within a range of 0.0005 to 0.006 N butyric acid. 

 If the exposure is too short membrane formation will 

 occur without normal development. ^ 



All this leads us to the conclusion that the main 

 effect of the spermatozoon in inducing the development 

 of the egg consists in an alteration of the surface of the 

 latter which is apparently of the nature of a cytolysis 

 of the cortical layer. Anything that causes this altera- 

 tion without endangering the rest of the egg may induce 

 its development. The spermatozoon, therefore, causes 



* Loeb, J., Artificial Parthenogenesis and Fertilization, 1913, p. 250 

 and Jf. 



' Delage, Y., Arch. d. Zool. exper. et gen., 1902, x., 213; 1904, ii., 27; 

 1905, iii., 104. 



3 Lillie, R. S., Jour. Biol. Chem., 1916, xxiv., 233. 



