22 BOTANICAL GAZETTE [JULY 
mosomes, the two arms of each loop forming a bivalent chromo- 
some (figs. 87, 88). After becoming completely detached from the 
membrane, 22 bivalent chromosomes are scattered throughout the 
cavity. 
The synaptic phase (figs. 79-87) illustrates the mode of origin 
of the bivalent chromosomes. The chromatin network of the 
resting stage, irregularly branched and thickened, becomes trans- 
formed into the chromatin fibrils in very early prophase, which 
grow more and more evenly thickened and continuous for con- 
siderable distances (fig. 79). This stage would show a double 
nature, if any such association of two individual fibrils occurs as 
a premature indication of later parasyndése in the formation of 
chromosomes, like that described for Lilium (GREGOIRE 10; 
BerGHs 3; ALLEN 2), Polysiphonia (YAMANOUCHI 19), and in 

‘8 if 
W 
Fic. 19.—~Apogamous sporelings two or three days old. 
be pe forms. Butin Zanardinia the fibrils are single (fig. 79). 
S gradually become transformed into chromatin threads 
(figs. 80, 81) which 
mes gather near the center (fig. 80) 
®quatorial plate (figs. gr-93). The 
chromosome separate and proceed to 

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