io8 



Scientific Proceedings (65). 



gelatin-Ringer's solution show that this is due for the most part 

 to differences in the fragility of the erythrocytes. Corpuscles of 

 the several species in question, protected with gelatin during 

 washing and placed in plain Ringer's, differ relatively little in their 

 period of survival. 



65 (997) 



Experimentally fused embryos with special reference to giant 

 larvae formation, changes of symmetry, and changes of 

 synchrony. 



By A. J. Goldfarb. 



[From the College of the City of New York.] 



Experimentally fused groups of two or more eggs of the sea- 

 urchin Arbacia punctiilata were studied individually from the 

 blastula stage through the larval stage as late as the 14-day larvae. 

 These isolated groups were studied with respect to the behavior 

 of the three major tissues, body wall, gut and skeleton, and, of the 

 processes taking place I wish to mention briefly only three. 



1. Contrary to the views of Boveri and DeHaan two fused 

 eggs may develop into a single giant larva even when the axes and 

 symmetry of the two eggs or blastula or gastrula are not in the 

 position of two blastomeres of an egg. A considerable number of 

 fused pairs of eggs were followed through their entire development, 

 in which the axes of the two numbers diverged 35 to 135 degrees 

 from each other, yet these eggs gave rise to single giant larvae. 



Some of the processes involved in the transformation of two 

 asymmetrically fused eggs include (1) change of symmetry, 

 (2) retardation, (3) repression of one of the members, (4) absorp- 

 tion of one or more parts, (5) conflict of the skeleton centers, 

 (6) size and rate factors in development. 



2. There is a definite tendency for the two members to grow 

 unequally, the one becoming increasingly small, though the rate 

 of development is little or not affected. The law of synchrony as 

 developed by recent investigators certainly does not apply in 

 these grafts, and the regulative changes are due in largest part to 

 the other factors enumerated. 



