303 
Smith . — A Note on Conj ligation in Zygnema . 
The nucleus is approximately double the size of the vegetative nucleus 
(7-8 fx), and frequently appears constricted. Whether this appearance is 
due to incomplete fusion or incipient division was not determined. 
The cytoplasm is much vacuolated, with many highly refractive 
droplets which dissolve completely in absolute alcohol .or ether, and so 
would seem to be of an oily nature (Text-fig. 2, a). 
Occasional azygospores are found, which are more ovoid, and contain 
Text-fig. 2. a. Young zygospore of Z. stellimim , showing four chloroplasts and fusion 
nucleus in centre of spore, b. Young azygospore, ovoid, with only two chloroplasts. c. Mature 
zygospore, showing sculpturing of the mesosporium : the four chloroplasts remaining distinct. 
(All x 1,300.) 
only two plastids. The nucleus also is no larger than the vegetative nucleus 
(Text-fig. 2, b). 
The mature zygospore (Text-fig. 2, c) shows sculpturing of the 
mesosporium into blunt bosses, which are yellow-brown and cuticularized. 
The four chloroplasts retain their individuality : even at this stage there is 
no sign of any fusion or division of the plastids. The four tetrahedrally 
arranged ingrowths on the wall may indicate a subsequent tetrad division, 
similar to that described in Spirogyra (Trondle (2)), for the first division 
of the zygote, but this point must be left for further observation to 
decide. 
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