DEVELOPMENT OF EGGS OF ARBACIA AM) t H.E K H'TKRUS. 287 



When multipolar spindles formed in the eggs as a result of 

 their treatment with a 2 per cent, solution of alanin the eggs, 

 apparently, were nevi-r al>le to divide, although there seemed to be 

 a long period during which active .ind resting si - 'Iternatcd 

 with each other. In the- re-tinu stages the eggs contained either 

 one lar^e. oblong nu< leu-, or -e\ era! -mailer ones that were more 

 or less irregular in outline. In the active period- one lai 

 multipolar spindle \\ith hundred- of chromosome- scattered 

 about it wouUl be formed, or -e\eral small spindles, all more or 

 less irregular, would be -cattered throughout the cell. In some 

 of these eggs a number ol ssory asters were formed, -imilar 



to those that Morgan ('96, '<)<)) found could be produced in the 

 eggs of Arbacia and of variou- other lonn- by mean- of -alt 

 solutions. 



A 2 per cent, solution of alanin produced greater abnormalities 

 in the eggs of Chcctoptcrus than did any of the other -olutioii- >! 

 amido-acids that were used, but as the-e abnormalitie- were "i 

 the types that can be produced in dillerent kind- ol by 



itmcnt with various salts they cannot be cmi-idered a- the 

 i ult of any specific action on the part of the alanin. 



SUMMARY AND COM u SIGNS. 



With the exception of cystin, which i- a sulphur-containi 

 compound, all of the amido-acids u-ed in the-e e\p< rimeni- 

 com posed of the same chemical elemeiu-. yel ihe\ diller to .1 

 marked extent in their toxic action on de\elopiiu < ,lu- 



tamic acid and aspartic acid are by far the nio-t iiijuriou-, e\en 

 per cent, solution of the-e substances killing ih< !' both 



Arbacia and of Chcctopterus at a ver\ early periml. ( ilyco-<II, 

 on the other hand, permits of the de\elopment of normal plutci 

 and t rochophores, and onl\- injures the embryos after t went y- ton i- 

 hours. The other amido-acid- u-ed retard de\ el. ipment , to a 

 ,ier or less extent, depending chielly upon the -treii^th o| 

 the -olution employed. 



\ brief summary of the effects oi the \ariou- -ulution- ot 

 amido-acids on the development of the e^-- of Ar/xicia and of 

 Chd'topterus during the tir-t t\\el\ e Imur- i- ^ivcn in the tollow iu^ 

 table. I'ltimately all of the solution- are toxic, even though 

 the\ appi-ar to fa\-or development during an early period. 



