196 ARTIFICIAL PARTHENOGENESIS AND FERTILIZATION 



of the heavy precipitate of BaS0 4 that is formed in this case, 

 hence I have not performed so many experiments with barium. 

 Curiously enough Mg and Ca do not help the formation of 

 a membrane with mammalian blood. 



TABLE XXXVII 



The efficacy of Dendrostoma blood, however, was not in- 

 creased by the addition of strontium. 



3. This method of sensitizing was improved by putting the 

 eggs for some time into a 3/8 m solution of SrCl 2 and then 

 exposing them to the serum. 1 The eggs are first washed in 

 a NaCl solution and then put into a 3/8 m solution of SrCl 2 . 

 After from five to ten minutes (or if necessary later) a drop of 

 eggs is taken from this solution and put into a mixture of 1 c.c. 

 sea-water and 1 c.c. serum (rendered isosmotic with sea-water). 

 In this way by a sufficiently long treatment with SrCl 2 the eggs 

 of practically every female can be sensitized against foreign 

 blood. The same method was found effective for the eggs of 



1 Loeb, "Die Sensitivierung der Seeigeleier mittelst Strontiumchlorid gegen 

 die entwicklungserregende Wirkung von Zellextracten," Archiv f. Entwicklungs- 

 mechanik, XXX, 44, 1910. 



