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UNFERTILIZED STARFISH EGGS. 307 



develop and live beyond the bipinnarian stage, inhibits the 

 maturation of the immature egg". When the in a tit re unfertilized \ 

 esrsfs of a starfish are introduced for fifteen to sixtv minutes into 



oo 



a mixture of 100 c.c. sea water plus 3 c.c. n/io HC1 ninety per 

 cent of the eggs can, under favorable conditions, develop into . 

 larvse. If, however, the eggs are introduced into such a solution 

 for the same length of time before maturation, the maturation of 

 the eggs is prevented either permanently or for a long time. 1 

 The difference is still more striking when the eggs are kept for a 

 shorter time in a mixture of 100 c.c. seawater and 5 c.c. n/io 

 HC1. This shows that acid affects the process of development 

 and the process of maturation in opposite or at least different 

 ways. 



Y\ e must now raise the question. How does the behavior of 

 naturally parthenogenetic eggs, such as the eggs of bees har- 

 monize with these ideas? 



In naturally parthenogenetic eggs it seems as if the processes 

 which underlie maturation pass over into those underlying 

 development. But it is possible that this is only apparently the 

 case, and that in reality it so happens that in the processes under- 

 lying maturation a metabolic product is formed in the partheno- 

 genetic animals which favors the processes of development. We 

 know that an exceedingly small amount of hydrogen ions suffices 

 to bring about development in unfertilized starfish eggs ; that an 

 exceedingly small amount of calcium causes the unfertilized eggs 

 of Auipliitrite to develop; and that a trace of potassium ions 

 brings about the development of unfertilized Chtetoptcrns eggs. 2 

 It is entirely possible that the specific ions or other substances 

 necessary to start the development of the eggs of the bee are 

 formed within the egg itself through the chemical changes taking 

 place during or after maturation, and that without the forma- 

 tion of these substances development is impossible. In the case 

 of sea-urchins and starfish eggs one might also believe that 

 the processes of maturation and the processes of development pass 

 over into each other. For it has often been observed that the 



1 The eggs which finally maturate in spite of the previous treatment with 

 acid often begin to cleave when maturation is complete and develop into 

 larvae, while the control eggs kept in normal sea water do not develop. 



2 Loeb, Fischer and Xeilson, /. c. 



