652 STUDIES IN GENERAL PHYSIOLOGY 
cane-sugar was a 2n solution, while my NaCl solution was 
24n. On account of the electrolytic dissociation, more than 
30 c.c. of the cane-sugar solution were required to produce 
the same increase of osmotic pressure as by 15 c.c. of the 
24n NaCl solution. The following solutions were tried: 
(1) 40 cc. 2n cane-sugar-+ 60 c.c. sea-water 
(2) 20 (73 “ + 80 “ 
(8) 10 T3 (73 + 90 c 
(4) 10 24nKCl +90 « 
(5) Normal sea-water (control) 
The eggs remained fifty-five minutes in these solutions. 
Eight hours later swimming ciliated trochophores were found 
in the eggs that had been in solutions 1 and 4. In 2 and 3 
there were no swimming larve. In the control material all ° 
the eggs were still spherical and unsegmented. The next 
morning about 25 per cent. of the eggs that had been in 
solution 1 swam about in the most lively manner. <A few 
trochophores were found among the eggs that had been in 
solution 2. But the control eggs and the eggs that had 
been in solution 3 had in the best case only reached the 
earliest stages of segmentation. This leaves no doubt that 
an increase in the osmotic pressure of the sea-water is 
sufficient to bring about artificial parthenogenesis in the 
eggs of Cheetopterus. 
Sixth series.—In order to make this conclusion stronger, 
it was necessary to try the effect of an increase in the osmotic 
pressure of the sea-water by the addition of still other sub- 
stances. The following were tried: 
(1) 5ee.5n CaCl, +95 ¢.c. sea-water 
(2) 10 cet ne +90 “« 
(3) 10 24n MgCl, +90 “ 
(4) 20 “ 79 +80 ce 
(5) 30 *§ 499 “ 
(6) Normal sea-water (control) 
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