DIRECT ASSIMILATION OF ORGANIC CARBON BY 
CERATODON PURPUREUS'! 
WILLIAM J. ROBBINS 
(WITH FIVE FIGURES) 
Considerable attention has been devoted in recent years to the 
investigation of the assimilation by green plants of carbon in 
organic form. Attention has been directed to this phase of plant 
physiology because of the renewed interest in the relation of the 
organic compounds found in the organic material of the soil to the 
_ growth of green plants, and also because of the light which the result 
may throw on the question of the products formed in photosyn- 
thesis and of the function of various organic compounds in plant 
metabolism. A number of investigators have shown that higher 
plants may absorb and assimilate many organic compounds. In 
1914 the writer began an investigation of the assimilation of organic 
compounds by the mosses. Circumstances made it impossible to 
complete the investigation. The results, however, show some 
facts and may prove suggestive to those who may continue the 
work. 
SERVETTAZ (6) and von Usiscu (7) have made observations 
upon the assimilation of organic carbon by the mosses. SER- 
VETTAZ grew several species of mosses under sterile conditions 
on various solid and liquid media. Most of his work was done 
with Hypnum purum. According to SERVETTAZ the mosses when 
furnished with sugar or some other organic substance are able 
to live in the dark and become green slowly; but under these 
conditions they do not form starch and their increase is never 
important. Levulose, lactose, maltose, and saccharose when 
present at a concentration of 5 parts per 1000 favor development, 
but 2 parts per roo are decidedly toxic. Dextrine, starch, and 
gum arabic at a concentration of 5 parts per 1000 retard develop- 
ment, but at 2 parts per 1000 favor it. Hypnum purum prefers the 
* Published by permission of the Director of the Alabama Agricultural Experi- 
ment Station. 
543] [Botanical Gazette, vol. 65 
