ARTIFICIAL PrRopucTIon oF NorMAL LARV®e 587 
through the changes of cell-division and assimilation re- 
quired for the process of development. I next tried whether 
it was necessary that the Ca and K ions be added in equal 
proportions to the NaCl. Table IT gives the results of such 
experiments. 
It is obvious that the proportion of K and Ca ions may 
vary within certain limits as long as they are present in 
sufficient quantity. I will add that I have not yet found any 
other combination of three chlorides that yields swimming 
blastule. In the foregoing papers I mentioned that the 
anions are not indifferent, and that in a NaBr solution the 
rhythmical contractions of a muscle begin even sooner than 
in an equimolecular NaCl solution. I made some experi- 
ments on the effect of bromides on development. In a solu- 
tion of 96 cc. 3n NaBr + 2 cc. 8n KCl+ 2.0. 32n KCl 
the eggs developed into normal blastule. In a solution of 
96 cc. LiBr+2 ¢.c. CaCl, + 2 ¢.c. KCl the egps reached 
the sixteen-cell stage, while in the corresponding LiCl solu- 
tion practically no segmentation took place. All these ex- 
TABLE II 
Nature of the Solution Used Stage Dee cericet 
1..| 96 c.c. §n NaCl + 2¢.c.8n KCl 2¢.c. 49 n CaCl, | Normal blastula. 
Ds ee +2 +1 « Normal blastula. 
3. ‘6 ze «“ +4 ‘“ Normal blastula. 
4_. “ +1 “ +23 “ Normal blastula. 
5 « +4 “ +2 “ Normal blastula. 
6. “ +1 “ +1 “ Normal blastula 
developed a 
little more 
slowly. i 
7... “ + “ +4 7 No blastulee. 
5 Stopped at 8- 
32-cell stage. 
periments together give us the impression that different com- 
binations of ions may exist which all have the same effect. 
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