100 ArRrriFIcIAL PARTHENOGENESIS AND FERTILIZATION 
formation. If eggs fertilized with sperm are placed in 50 e.e. 
of sea-water, to which increasing amounts of 2 m NaCl are 
added, it can be seen that the addition of 1 ¢.c. of 25 m NaCl 
to 50 ¢.c. of sea-water has no effect on the development; the 
addition of 2 c.c. of 23m NaCl retards the first division, but toa 
scarcely noticeable degree; while the addition of 3 c.c. increases 
TABLE VIII 
,PERCENTAGE OF Eacs THaT DEVELOPED INTO LARVAE 
| AFTER REMAINING IN THE SOLUTION 
NATURE OF THE SOLUTION 
37 ATe eon 110 | 150 200 280 340 
| Min. | min. | min. | min. | min. | min. | min. | min. 
50 c.c. of sea-water+2 c.c. 
De sme Nia © lise anette race 0 0) 
50 c.c. of sea-water+3 c.c. 
Dewy Nia Cl ence ee ses creas 0 0 0) 0 0 0 0) 0 
0 
0 
50 ¢.c. of sea-water+4 c.c. 
2 Tare Nia © lease vr ete ae 
50 c.c. of sea-water+5 c.c. 
0! 30; 50] 80] 90} 90} 40 
Qe Nia © leas ee eee 
50 ec.c. of sea-water+6 c.c. | 
Pest NEY Ole bxpo ob. conan c = os 80 95 
50 c¢.e. of sea-water+8 c.ce. | 
Dearie Nia Ole ats tcc ee 0 10 | 100 
50 c.c. of sea-water+10 c.e. 
tim Na Ole sSeaa ee cae a.few| Sz) S30c)-c- | 
50 ¢.c. of sea-water+12 c.e. 
DarriaiNa © liter eres ees ecyerecsse 0 1 2 0 0 0 0 0) 
50 c.c. of sea-water+14 c.c. 
DMNA © lem gacceseee ony oe 0 0 0 Ila few) 0 0 0 0 
the time of the first division by about 12 per cent of its usual 
length, although the development of the eggs proceeds almost 
normally. The addition of 4¢.c. of 24 m NaC! to 50 c.c. of 
sea-water is the first to delay the first cleavage for several hours 
(over 100 per cent of the normal length); it is true that the eggs 
can develop very slowly in this solution, but not all the eggs are 
able to develop. Hence it appears that here too the addition 
of 4.c. of NaCl is of critical importance. In 50 .c. of sea- 
water+5 ec.c. 24 m NaCl the eggs do not develop beyond the 
thirty-two- to sixty-four-cell stage. Probably, therefore, in a 
