10 
AMERICAN JOURNAL OF BOTANY 
[Vol. 8 
growths, and nos. 2 and 5 "fair." Species nos. 3 and 7 were not included 
in this series. 
Series gA (calcium nitrate, with i percent glucose). Development was 
very vigorous from the start, all cultures soon producing a complete coat 
over the agar surface. At the end of a month, species nos. 3, 5, 6, and il 
began to turn yellow. The deterioration, however, did not progress far, 
and after another month or two all cultures were again green, remaining 
healthy until analysis. Species nos. 1,2, and 7 remained healthy throughout 
the entire growing period. At the end of the experiment a "luxuriant" 
growth had resulted with species nos. 2 and ii, "very good" growth with 
nos. I, 5, and 6, "good" with no. 3, and "slight" with no. 7. 
Series gB (calcium nitrate, with i percent mannite). The development 
was very similar to that in series 9, being slow but steady. All cultures 
remained healthy to the end. Species nos. i and 11 produced "very fair" 
growths, nos. 2, 5, 6, and 3 "fair," and no. 7 only "slight." 
It should be noted that in the 191 7-1 8 experiment the development of 
the four species on the two nitrate media with glucose (series and 5^) 
was very similar, the growth being either "luxuriant" or "very good" in 
all cases. Of the two, however, the cultures of series 5A appeared some- 
what the better. In striking contrast with this condition was the growth 
of the various species on similar media of the 1919 experiment (series 8^ 
and ()A). The species which gave such good growths on ammonium 
nitrate with glucose (series 4^) in 191 7-1 8 showed scarcely any develop- 
ment on this medium in 191 9 (series 8^4), with the possible exception of 
species no. 5. However, on calcium nitrate with glucose (series 9^) the 
growth of these species was practically the same as was secured on the 
similar medium of I9i'7-i8 (series 5^). Even though a few of the flasks 
of series 8^ were reinoculated, the growth continued poor; likewise, 
"reserve" flasks of this medium which were not introduced in the series 
at the beginning of the experiment gave very similar growths of species 
nos. I and 2 when inoculated a few months before the end of the growing 
period. This difference in the amount of growth produced in the two experi- 
ments may possibly be related to the difference in the seasons during which 
the experiments were conducted. 
Analyses 
At the end of a growing period of from six to eight months the cultures 
and checks were analyzed for total nitrogen content. After making a final 
record of the growth and condition of the cultures, a small loop of the algal 
material from each flask was transferred to a drop of sterilized nutrient 
solution and examined microscopically. In 191 8 transfers were also made 
from each culture to nutrient agar containing i percent glucose, and to the 
same medium made acid by the addition of I percent hydrochloric acid. 
Two tubes of each of these media wete inoculated from each culture flask, 
but in no case did contaminations appear that were not apparent from the 
