ARTIFICIAL PARTHENOGENESIS AND OXIDATIONS 121 



increase is so small that it is not likely to be responsible for the 

 corrective action of the hypertonic solution. 



It is more probable that the treatment of the egg with the 

 hypertonic solution brings about a permanent change in the 

 egg by which it can now undergo the process of membrane 

 formation at any time without danger of subsequent disinte- 

 gration. This irreversibility of the corrective effect of the 

 hypertonic solution would be intelligible on the assumption 

 that it is due to the formation of a definite substance which is 

 retained by the egg and which is a preventive against the 

 disintegration following membrane formation. 



7. We may here discuss parenthetically a hypothesis put 

 forward by R. Lillie 1 concerning the nature of the corrective 

 action of the hypertonic solution. Lillie suggests that the 

 essential feature in the act of fertilization is an increase in 

 the surface permeability of the egg of which the membrane 

 formation is the consequence; and that the effect of the "after- 

 treatment with a hypertonic solution is to bring the permeability 

 again to normal." 



We are able to investigate the relative permeability of 

 fertilized and unfertilized eggs for bases with the aid of a 

 color test, and this color test shows that both unfertilized as 

 well as fertilized eggs are permeable for weak and impermeable 

 for strong bases. 2 As far as acids are concerned, the fact 

 found by the writer that weak acids like C0 2 and the fatty 

 acids cause membrane formation in the unfertilized egg shows 

 that such an egg must be permeable for these substances. 

 McClendon 3 has published experiments which he thinks sup- 

 port Lillie's view of an increased ion-permeability of the egg 

 after membrane formation, but the writer does not feel 



1 R. Lillie, Jour. Morphol., XXII, 695, 1911; Am. Jour. Physiol., XXVII, 

 289, 1911. 



2 O. Warburg, Zeitschr. f. physiol. Chem., LXVI, 305, 1910; N. Harvey, Jour. 

 Exper. Zool., X, 507, 1911. 



s McClendon, Am. Jour. Physiol., XXVII, 240, 1910. 



