284 HELEN DEAN KING. 



material showed that ty rosin acts on the eggs of Chcctopterus as 

 it does on the eggs of Arbacia, causing a marked retardation in 

 development but producing no specific abnormalities. 



Glntamic Acid. Solutions of various strengths (i, \ and yg- 

 per cent.) were used, the eggs being placed in the solutions about 

 three quarters of an hour after their fertilization. All of the 

 eggs in the two stronger solutions were evidently killed at once 

 as none of them made any attempts to divide. Some of the eggs 

 in the ^ per cent, solution began to elongate after the solution 

 had acted upon them for one hour, and later many of these eggs 

 took on an irregular shape as if attempting to divide into several 

 cells at the same time. None of these eggs had segmented after 

 five hours, however, so they were all returned to normal sea- 

 water in the hope that they would then be able to continue their 

 development. There was no segmentation of any of the eggs, 

 although they appeared to live for some hours. 



Sections of preserved material showed that the segmentation- 

 spindle had formed in many eggs in an apparently normal manner, 

 but that development had been stopped at this point. 



Aspartic Acid. Eggs of Chcetopterus fertilized at 10.55 A.M. 

 on August 8, 1909, were placed in solutions of aspartic acid (i, 

 ~2~> iV ar >d sV per cent.) at 11.25 A.M. The eggs in the control 

 culture were segmenting at 11.55 A.M., but no evidence of cleav- 

 age could be detected in any of the eggs in the aspartic acid 

 solutions until 1.30 P.M., when a few of the eggs in the ^ per 

 cent, solution began to elongate as if about to divide. A number 

 of these elongated eggs were isolated and carefully watched for 

 some time, but in no case did any division occur. Sections of 

 preserved material showed that some eggs contained a normal 

 segmentation-spindle, while others had a multipolar spindle that 

 occupied an eccentric position close to the periphery. The 

 stronger solutions of aspartic acid killed the eggs before the 

 formation of the segmentation-spindle. 



Asparaine. Solutions of this substance of the same strengths 

 as those used in the experiments with aspartic acid were tested. 

 Normal cleavage began in the eggs of all of the cultures at the 

 same time as in those of the control lot. Observations made at 

 frequent intervals durine the next lour hours showed that seg- 



