56 BOTANICAL GAZETTE [yuLy 
into two lots of equal number, one lot being put aside in the dark for a 
few days and the other steam-sterilized for two or three hours on three : 
successive days. This sterilization proved thorough so far as blue-green 
algae are concerned, since none developed in the dishes. A certain amount 
of infection is unavoidable, and a few cultures in each lot had to be thrown 
away because of the development of some ‘‘damping-off” fungus. But _ 
on the whole the plants in my cultures have done quite as well as those _ 
out of doors. During the growing season now ending they did better than 
those out of doors, because November and December were cold and dry. 
Eleven or twelve weeks after sowing, the small plants already beat 
archegonia and antheridia when the cultures are kept under suitable con- 
ditions of illumination. Cultures kept too dark will contain few if any 
fruiting plants, though the plants may be normally large. From this 
fact, though I have not attempted to support this view by further investi- 
gation, one may infer that light acts as a stimulus to the development of 
the reproductive organs as V6CcHTING! and KiEBs? have shown to be the 
case in certain flowering plants and fresh-water algae. 
On comparing the young plants on sterilized and on unsterilized soil 
the greater size and more robust appearance of the plants on sterilized soil 
is evident. The plants on sterilized soil contained no Nostoc colonies. 
The plants on unsterilized soil contained Nostoc colonies, few of them 
bore reproductive organs, and they appeared less thrifty. But the young 
Anthoceros plants on unsterilized soil were obliged to compete not only 
with .each other but with several other sorts also. Without attempting 
an exhaustive list of these other plants I may record the presence, in the | 
cultures, of prothalli of Gymnogramme tiriangularis, fronds of Fimbri- — 
aria Calijornica, two or three small mosses, both protonemal and adult, — 
some green algae (especially a small Vaucheria), some blue-green algae i : 
(Nostoc, Oscillatoria, Anabaena), chickweed, and grass. Besides these, 
which started from spores, seeds, or other resting stages, there were small | 
plants which had held over the dry season as CAMPBELLS has described, | 
fern prothalli and plants of Fimbriaria and Anthoceros. % 
Where young plants of Anthoceros have to compete in small cultures — 
with such a number of individuals and of kinds of already fairly estab- 
lished plants, it is natural to assume that this amount of competition may 
Go ala ie 
* VécuTING, H., Ueber den Einfluss des Lichtes auf die Gestaltung und An lage 
der Bliithen. Jahrb. Wiss. Bot. 25: 149. 1893. : 
2 Kiess, G., Die ‘Bedingungen der Fortpflanzung bei einigen Algen und Pilzen. Hi : 
Jena, 1896. 
3 CAMPBELL, D. H., Resistance of drought by liverworts. Torreya 4:81. 1904+ 
