31 
Colorado Experiment Station. 
5-15 mic. in diameter, yellow green, often changing to shades of red by 
exposure. This is the common green alga found everywhere on soil, moist 
rocks, walls, trunks of trees, etc. In the soil capillarity tube, the orange 
yellow or reddish brown spots are due to this species. 
Navicula sp. (Diatom) Plate IT., fig. 18. Soil sample 10. Plants brown¬ 
ish. boat-shaped, bivalved. the valves marked by fine, parallel striations; 
individuals 4 8-5.2 mic. in diameter. 28-68 mic. long. 
DESCRIPTIONS OF FLASK CULTURES. 
Here follows a brief description of the general nature of the 
algal growth and an enumeration of the soecies occurring in each 
flask. All flasks were inoculated between November 25 and 28, 
1911. In some cases a slight green tinge to the water or qua r ‘' r 
surface appeared within one month after inoculation. In most 
cases, however, no growth was apoarent until the first Dart of Feb¬ 
ruary, 1912. The abundant development of the algae in sampe No. 
1 is typical of the majority of cases. Plate IV., fig. 10 is a water 
color drawing of this flask culture. 
Sample No. 1.— SOIL: heavy clay, orchard. GROWTH : vigorous, 
covering the surface of the sand with a dark green coating and extend¬ 
ing several centimeters above and below the sand surface on the sides 
of the flask. In places the growth is brownish-black, due to Stigonema. 
AT.GAF: Nostoc “A”, Nostoc “B”. Nostoc commune, Anabaena “A”, 
Stigonema sp. 
Sample No. 2—SOIL: sandy loam, orchard. GROWTH: at first 
blue-green, becoming grayish-green or yellowish in color; covering quartz 
and water surface and sides of flask. ALGAE: Nostoc “B”, Nostoc 
commune. Anabaena “A”, Rivularia “A”. 
Sample No. 3.—SOIL: sandy loam, orchard. GROWTH: none. 
Sample No. 4—SOIL: sandy loam, orchard; GROWTH: substratum 
covered with a yellowish-green scum. ALGAE: Phormidium tenue, 
Nostoc “B”, Nostoc “CL 
Sample No. 5.—SOIL: sandy loam, orchard. GROWTH: substratum 
wholly covered with a dark green mass; algae also extending for some 
distance below the sand surf?ce along the sides of the flask. ALGAE: 
Nostoc commune, Anabaena “A”. 
Sample No. 6.—SOIL: clay loam, orchard. GROWTH: substratum 
entirely overgrown, at first blue-green becoming vellowish green. AL¬ 
GAE: Nostoc “B”. 
Sample No. 7.— SOIL: sandy loam, orchard. GROWTH: the first 
evidence of algal growth appeared in this sample; this was one month 
after inoculation and was due to the unicellular green alga. The scum 
occurred on the quartz, water and sides of flask. ALGAE: Rivularia 
“A” Stigonema sp., unicellular green alga. 
Sample No. 8.—SOIL: clav loam, orchard. GROWTH: scanty; scum 
thin. ALGAE: Nostoc “B”, Nostoc commune. 
Sample No. 9.—SOIL: clay loam, orchard. GROWTH: substratum 
covered with a grav-green scum: algae also extending noon the sides of 
the flask. ALGAE: Phormidium inundatum, Nodularia harveyana, 
Nodularia “A”, Stigonema sp. 
Sample No. 10.— SOIL: clay loam, orchard. GROWTH: rdant mass 
blue-green covering the entire substratum. ALGAE: Phormidium in¬ 
undatum, Phormidium subuliforme. Phormidium tenue, Nostoc “A”, Nos¬ 
toc “B”, Anabaena “A”, Navicula. 
