96 EDWIN G. CONKLIN 
Fig. 25 Same slide as preceding. The minute protoplasmic ‘macromeres’ 
(A and D) have divided equally into the macromeres 1A and 1D and the micro- 
meres Ja and Jd. The other macromeres (B and C) have given rise to micromeres 
somewhat larger than usual. 
Fig. 26 Centrifuged for thirty minutes during the second cleavage; fixed twelve 
hours later; the nuclear divisions of the second cleavage were completed, but the 
cell divisions were suppressed. Each of these two binucleate macromeres has 
given rise to two first, and two second quartet cells, just as if four macromeres 
were present, and each of these micromeres has subdivided in approximately nor- 
mal manner and is uni-nuclear. 
Fig. 27 Centrifuged for thirty minutes in 2-cell stage; fixed six hours later. 
Micromeres formed from protoplasmic macromeres are of the same size as those 
formed from large yolk macromeres. 
Fig. 28 Same as preceding. The regulation in the formation of micromeres 
is complete. 
