Vol. XLIIL August, 1922. No. 2. 



BIOLOGICAL BULLETIN 



THE EFFECT UPON DEVELOPING EGGS OF EX- 

 TRACTS OF EMBRYOS OF THE SAME SPECIES. 1 



MARY GRACE SPRINGER. 



PAGE. 

 I. Introduction ................................................ _ - 



II. Methods and materials ....................................... yg 



III. Effects of embryological extracts on the growth of the early stages 



of the egg of Arbacia ................................... yg 



1. Effect of extracts made up in a solution of sea water. 



2. Effect of extracts in solutions of agents other than sea water. 



IV. Analysis and discussion ...................................... qj 



V. Summary .................................................... * 



VI. Literature cited .............................................. nr 



INTRODUCTION. 



The investigations described in this report are an attempt to 

 isolate formative substances from the early embryological stages 

 in the developing egg of Arbacia punctulata. Upon the hypothesis 

 of formative stuffs, egg extracts should show the presence of 

 such materials, if under the conditions of the experiment they 

 are isolable. Since development is conceived of as a series of 

 exceedingly complex reactions involving both chemical and phys- 

 ical factors, the formative substances present in the fertilized egg 

 must be the substances which begin this long sequence of reac- 

 tions. If by their action and interaction, other and possibly more 

 complex substances are synthesized, then at a given stage in de- 

 velopment we should expect to find in the extracts of the larvae 

 the formative substances of that period, provided of course they 

 go into solution in the solvents used. If such is the case, it 

 seems decidedly important to find out whether by treatment of 

 fertilized eggs with extracts of larvae at a given stage, it is pos- 

 sible to accelerate the development of the eggs when they reach 



1 Contribution from the Zoology Department, Oberlin College and the 

 Marine Biological Laboratory. 



75 



