176 



FRESH-WATER BIOLOGY 



4 (3) Plant a steel blue, brownish or red, consisting of a single, branched 

 row of cells, the branches of the same structure as the 

 principal axis, irregularly placed and not in whorls. 



Cliantransia Fries. 



Sexual reproduction resembling that of Batracho- 

 spermum; carpogonia on lateral branches; tetra- 

 spores resembling carpospores on the tips of cells. 

 Plants dioecious. 



Fig. 250. 



Chantransia chalybea Fries. X igo. 

 (After Kirchner.) 



5 (2) Branches in whorls. 



6 (7) Plant purplish or bluish, beaded in appearance, due to whorls of dichot- 

 omous, accessory branches, composed of a single chain of 

 cells on a pseudo-parenchymatous axis. 



Batrachospermum Roth. 



Plant several centimeters long; occasionally dioecious, the antheridia at the ends of acces- 

 sory- branches, the carpogonia frequently near the axis; the carpospores give rise to a proto- 

 nema on which the adult form may originate as a branch. The protonema may also give rise 

 to asexual spores which again may produce protonema. 



Fig. 251. 



Batrachospermum grabussoniense Sirodot. A . portion of plant. 

 X 225. C. procarp. X 580. (Original.) 



X about 25. B. branches. 



7 (6) Thallus erect, richly branched, several centimeters high; beaded 

 throughout, due to whorls of branches which are so closely 

 packed and grown together as to form a continuous outer 

 sheath, the diameter of which is greater opposite these 

 branches Tuomeya Harvey. 



Antheridia at the ends of branches, mostly at the nodes; carpo- 

 gonia in the axils of branches. This genus is synonymous with 

 Baileya of Kiitzing. 



Fig. 252. Tuomeya fluviatalis Harvey. X 375- (After Sctchell.) 



