416 KING. [Vou XIX. 
first polar spindle when the twelve chromatin rings break into 
granules which cannot be distinguished from the granular 
achromatic substance of the nucleus. The twelve bivalent chro- 
mosomes that are finally formed from the mass of chromatin 
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A.—Diagrams showing the changes in the shape of the chromosomes of 
the first polar spindle in the egg of Bufo and the direction of the 
maturation mitoses. In both mitoses the chromosomes are 
divided longitudinally. 
B.—Diagrams showing the character of the maturation mitoses if the 
chromosomes were united end to end in synapsis. The first 
division separates univalent chromosomes; the second is a longi- 
tudinal division. 
C.—Diagrams showing the character of the maturation mitoses if the 
chromosomes conjugated side by side during synapsis. Both 
_ mitoses divide the bivalent chromatin segments longitudinally. 
granules that surround the polar spindle vary somewhat in 
size and in shape. When they have become arranged on the 
spindle they undergo considerable modification in form, and 
the longitudinal axis of the chromosome at the time that the 
