174 ARTIFICIAL PARTHENOGENESIS AND FERTILIZATION 



Shortly afterward my attention was again drawn to the 

 connection between membrane formation and cytolysis, when 

 performing experiments upon the effect of benzol and amylene 

 upon the unfertilized sea-urchin eggs. Here too it turned out 

 that the first effect of these hydrocarbons was, as Herbst 1 had 

 already observed, the formation of a fertilization membrane, 

 but this was followed almost at once by the cytolysis of the egg. 2 

 I found that if the eggs are removed soon enough from the 

 sea-water containing benzol or amylene, they can be caused to 

 develop into normal larvae after a short treatment with a hyper- 

 tonic solution. A similar result was obtained in experiments 

 upon the artificial membrane formation by the higher fatty 

 acids, and we shall return to this again. 3 



We will now discuss the series of different cytolytic reagents 

 from the point of view of their membrane-forming effect, and 

 we will start with the first group, that of the specific haemolytic 

 substances such as the glucosides (saponin, solanin, digitalin), 

 bile salts, and soaps; in this group belong the foreign sera, 

 to the consideration of which a special chapter will be devoted. 

 We shall start with a description of the effect of saponin upon 

 the sea-urchin egg. 



2. Figs. 39 to 45 are camera drawings of the changes of an 

 egg in a saponin solution (8 drops of a J of 1 per cent saponin 

 solution in sea-water to 5 c.c. of sea-water). Fig. 39 gives the 

 size and the appearance of the egg immediately after trans- 

 ference to the saponin solution (at 9:07 A.M.). Membrane 

 formation (Figs. 40 and 41) started four minutes afterward, 

 and at Fig. 42 a normal fertilization membrane had been 

 formed. Five minutes later, cytolysis starts, and indeed in 

 this case it depends upon a process which superficially and 

 in the beginning resembles membrane formation. For at G 



1 Herbst, Biol. Centralbl., XIII, 14, 1893. 



2 Loeb, "Ueber eine verbesserte Methode der kiinstlichen Parthenogenese," 

 Untersuchungen, p. 340. 



s Ibid., p. 342. 



