394 
BULLETIN OF THE UNITED STATES FISH COMMISSION, 
EXPLANATION OF FIGURES. 
Plate I. 
I. Chlarrtydomonas gracilis Snow. 
1.2. Motile cells. 
3. Gamete (?). 
4. Copulation of gametes?. 
I. Clilaniydomonas communis Snow. 
1-3. Motile cells. 
III. Chlamydomonas globosa Snow. 
1-5. Motile cells. 
IV. Scenedesmus. bijugatus var. jlexuosus Lemm. 
1. Coenobium of 32 cells. 
2. Resting stage. 
V. Staurogenia apiculata Lemn. 
1. Compound coenobium of 64 cells. 
2. Compound coenobium of 16 cells, showing 
gelatinous envelope as brought out by tan- 
nate vesuvine. 
3. Mass of cells from .05 per cent Knop’s solu- 
tion. 
4. Single coenobium in early stages of repro- 
duction, taken from an organic solution. 
(a) Nucleus, (b) Pyrenoid. 
5. Single coenobium. 
6. Diagram showing relative position of nuclei 
and pyrenoids in young ccenobia. («) Nuc- 
leus. (6) Pyrenoid. 
7. Membrane of a coenobium after daughter 
coenobia have been liberated. 
8. Cell showing nucleus and pyrenoid. 
(a) Nucleus. (6) Pyrenoid. 
Plate II. 
VI. Fusola viridis Snow. 
1- 4. Different stages in process of division. 
(a) Ruptured membrane of mother cell. 
3. Typical cells. 
VII. Oocystis borgei Snow. 
1. Single cell showing nucleus, a. 
2. Young cells from a culture in organic 
solution. 
3. Cells after division of chromatopliore. 
Taken from organic solution. 
4. Small colony taken from organic solu- 
tion. 
5. Single cell from 0.05 per cent Knop's so- 
lution, showing remnant of mother 
membrane, b. 
VIII. Chodatella citriformis Snow. 
1. Mature cell seen from side. 
2. Cell seen from end. 
3. Cell showing reproduction. 
IX. 1-4. Pleurococcus regularis Artari. 
1. Complex from the plankton. 
2- 4. Clusters from a culture. 
5. Coelastrum microporum Nag. 
Plate III. 
X. Pleurococcus ctquaticus Snow. 
1. Cell complex. 
2. Individual cells before formation of clus- 
ters. 
3. Complexes grown in collodion tubes. 
4. First stages in formation of complexes. 
5. Disintegration of the larger complexes. 
XI. Chlorococcum natans Snow. 
1. Mature cell. 
2. Gonidia formed in 0.2 per cent Knop’s solu- 
tion. 
3 Gonidia formed in 0.4 per cent Knop’s solu 
tion. 
4. Typical zoospores. 
5. Zoospores formed when material is trans- 
ferred from Knop’s solution to organic 
solution. 
6. Germinating zoospores. 
7. First stage in formation of zoospores. 
XII. Botrydiopsis eriensis Snow. 
1. Mature cell. 
2.3. Young cells. 
4. Gonidia formed from nonliberation of 
zoospores. 
5. Zoospores. (Freehand.) 
6. Germinating zoospores. 
7. Zoospores before liberation. 
XIII. Botrydiopsis oleacea Snow. 
1. 2. Mature cells. 
3,4. Younger cells of different shapes. 
5-7. Different stages in the formation of the 
zoospores. 
8. Zoospores. 
9. Germinating zoospores. 
10-11. Resting condition. 
Plate IV. 
XIV. Cldorosphcera lacustris Snow. 
1. Single cells. 
2. 3. Complexes arising from division. 
4. Zoospores. 
5. Germinating zoospores. 
6,7. Stages in the formation of the zoospores. 
XV. Cldorosphcera parvula Snow. 
1,2. Complexes formed by division. 
3. Zoospores. 
XVI. Mesocarpus spec. 
1. Normal filament. 
2. Filament under unfavorable conditions- 
XVII. Ccelosplicerium roseum Snow. 
1. Typical individual, a. Surface view. 
b. Interior view. 
2. Ccelosplicerium (?) showing free dichoto- 
mous gelatinous branches. 
XVIII. Chroococcus purpureus Snow. 
Showing mode of growth in small clusters 
embedded in gelatinous substance. 
