INTRODUCTION 
SS 
—<—<—$———=—=—. 
ISN 
X 350; c, after Cooke, 
ytonema ; b, Stigonema ; c, Gleo 
3; e, Rivularia. (a, b, e, after Kiitzing, 
Nostoc 
capsa ; 
Fie. ene erect alge that form gonidia. a, Se 
X 400; d, x 450.) 
™ 
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