12 TEE OBR DO'GONTA CEASE 
students of this algal family, and some of their names are found 
in the bibliography near the end of this monographic report. 
Some idea of the relative sizes of the three genera of the 
Oedogoniacee may be gained by a numerical recital of the 
composition of each. The genus Bulbochaete is composed of 
48 species, 15 varieties, and 7 forms, with 3 additional species 
having incomplete descriptions. In Oedogonium there are 
195 species, 76 varieties, and 38 forms; in addition there are 41 
species and 3 varieties incompletely known. Oedocladium, by 
far the smallest, has only 4 species recorded to date. 
Although an Oedogonium, a Bulbochaete, or even an 
Oedocladium can be recognized on vegetative characters alone. 
the identification to species is impossible, except in a very few 
cases, without reproductive organs. Such unusual forms as 
Oe.* undulatum, B. horrida, Oe. nodulosum, or Oe. reinschii 
are perhaps always recognizable in vegetative states, but such 
species are few in number. 
The comprehensive reports of Pringsheim (1858), Wittrock 
(1874), Hirn (1900, 1906), and Heering (1914) are not readily 
available to many students of the alge, and their points of 
emphasis have been necessarily European. The early Ameri- 
can accounts of the Oedogoniacee by Wood (1872) and by 
Wolle (1887) are quite unreliable. The work of Collins (1909, 
et seq.) made available much European literature and was the 
first American publication on the green alge that was really 
trustworthy. Perhaps to Collins should go the credit for the 
initiation of real interest in freshwater alge in North America. 
Unfortunately his papers were inadequately illustrated. It is 
hoped that furnishing a complete English treatise of the family 
Oedogoniacez, including in addition to the taxonomic consider- 
ation, a discussion of the more important features of structure, 
reproduction, and distribution, will not only aid the student 
in the study of these common alge but will stimulate added 
interest in algology generally. 
CELL STRUCTURE AND REPRODUCTION. 
The cell wall of the Oedogoniacee exhibits a rigidity not 
common to other filamentous Chlorophycee. The heavy 
cellulose layer is covered peripherally with pectose, and upon 

*The abbreviation Oe. as used in this paper refers to the genus Oedogonium, 
and not to Oedocladium. When the latter is meant, the abbreviation is O. 
