196 ArtriFicIAL PARTHENOGENESIS AND FERTILIZATION 
of the heavy precipitate of BaSO, 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 
Percentage 
of Eggs 
Composition of the Solution That 
’ Formed 
Membranes 
1 2 c.c. sea-water+1 drop ox serum. 5 
* |2 ¢.c. SrCL-+1 drop ox serum... .. 80 
sa) 2 c.c. sea-water +3 drops ox serum. 0 
2 ¢.c. SrCl.+8 drops ox serum.... 80 
3 1 c.c. sea-water+3 ¢.c. ox serum. . 14 
* \1 e.ec. SrCl,-+1 ¢.c. ox serum...... 33 
4 1 c.c. sea-water+1 ¢.c. ox serum. . 5 
1 c.c. SrCl,+1 ¢.c. ox serum...... 26 
5 jl c.c. sea-water+1 c.c. ox serum. . 8 
1 ¢.c. SrCl,+1 c.c. ox serum...... 50 
6 1 c.c. sea-water+1 ¢.c. pig serum.. 5 
' \1 ¢.c. SrCL+1 ¢.c. pig serum... .. 80 
me) 1 c.c. sea-water +1 ¢.c. pig serum.. 5 
* \1 e¢.c. SrCl.-+1 e:c. pig serum... .. 40 
8 {2 c.c. sea-water+2 c.c. dog serum. 0 
" \2 c.c. SrCl.+2 c.c. dog serum... .. 50 
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, and then 
exposing them to the serum.! The eggs are first washed in 
a NaCl solution and then put into a 3/8m solution of SrCly. 
After from five to ten minutes (or if necessary later) a drop ef 
eggs is taken from this solution and put into a mixture of 1 ¢.e. 
sea-water and 1 ¢.c. serum (rendered isosmotic with sea-water). 
In this way by a sufficiently long treatment with SrCl, 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. 
