themselves, out-turned fascicles of branches develop, those at the 

 node region forming primary whorls which in many species produce 

 a distinctly beaded appearance; cells in the axial row cylindrical, 

 ovoid, ellipsoid, or fusiform in the branches; branching of the fasci- 

 cles dichotomous, the ultimate branches terminating in short or 

 long colorless hairs; entire thallus inclosed in a soft amorphous 

 hyaline mucilage; a single massive chromatophore in each of the 

 principal cells, and two to five disc-like or irregular chromatophores, 

 each with a pyrenoid, in each cell of the branches; plant mass gray- 

 or violet-green or brownish. 



In this genus sexual reproduction involves female ( carpogonial ) 

 cells and male ( antheridial ) units. The latter are small, non-motile 

 cells produced in clusters at the tips of lateral branches. The carpo- 

 gonium is a flask-like cell with an elongate tip, the trichogyne, 

 which receives the spermatia. The shape and location of the carpo- 

 gonium and the form of the trichogyne are specific characters and 

 are of taxonomic value. The trichogyne may be spatula-shaped, 

 oblong, or lanceolate. See Kylin (1912), Sirodot (1884), and Skuja 

 ( 1931 ) for a description of sex-organ morphology in this genus. 



When reproductive organs are absent, identification of species in 

 Batrachospermum is practically impossible in most cases, and even 

 when such organs are present, experienced judgement is often re- 

 quired to make satisfactory determinations. Although there are 

 more than five species of Batrachospermum in our collections, 

 only those are listed here which have been observed in the fruiting 

 condition. An interesting problem involving the ecology and taxo- 

 nomy of this genus in this area awaits further studies. 



Batrachospermum forms dark gray-green or blue-green masses, 



streaming from stones or submerged wood in flowing or standing 



water, usually at low temperatures. Some species are less widely 



distributed than others and seem to be confined to acid ponds in 



Sphagmim bogs, where they produce growths up to 30 cm. in length 



on the submerged stems of Chamaedaphne or on overhanging 



grasses and sedges. Early in the summer, juvenile or Chantransia- 



stages predominate in certain habitats such as stones in flowing 



water. In this condition the young plants cover submerged objects 



with a blue-green gelatinous film. As mentioned under Audouinella 



above, comparison should be made between these juvenile stages 



of Batrachospermum and what may appear to be true Audouinella 



plants. 



Key to the Species 



1. Lateral whorls of branches lacking or scarcely developed; 



internodes long .— .— B. Dillenii 



1. Lateral whorls of branches well-developed, crowded; internodes short 2 



[566] 



