1918] ROBBINS—ASSIMILATION OF CARBON 549 
amount of dry matter. The dry matter of the moss grown in the 
solution containing levulose is much greater than that of the moss 
grown in the solution containing glucose. In the light twice as 
much dry matter was formed with levulose as the carbon source 
than with glucose as the source of carbon. In the dark there was 
produced in the levulose solution 7 times as much dry matter as 
was formed in the glucose solution. 
TABLE II 
: | 
Average d Original | 
Solution weight of sugar per patho Fong alght 
& m | gm, 
Levulose in HOME see else 0.0634 0.7700 | 0.1100 1.7 
OAR ue ees 0.0854 0.7700 | © 1650 1.9 
Ramone. ik Nene... 0.0345 0.8970 | 0.0440 3 
Cnccse i. Gath 5 a 0.0115 0.8970 | 0.0360 3.1 
Check, no organ ic carbon in light el OlObee foi aes Fare EU ae oe 
Check, no organic carbon in dark....| Inappre- |........-. | ee Gis ae aie epee 
Discussion 
It is evident that the moss used in these experiments can absorb 
and utilize organic carbon. The experiments do not demonstrate 
that the mosses under field conditions, in competition with both the 
bacteria and the fungi, benefit from the organic compounds in the 
soil. They do suggest, however, that if suitable organic compounds 
are present in the soil solution they will be absorbed and used by the 
moss with advantage. 
The results at present seem to bear little on the problems of the 
products formed in photosynthesis. It is an interesting fact, 
however, that starch was formed from the maltose and lactose, 
although no evidence was found that either of these sugars was 
hydrolyzed. They may have been hydrolyzed within the moss 
cells, or the products of hydrolysis may have been assimilated as 
fast as they were formed. In either of these cases evidence of the 
hydrolysis would have escaped the methods used in looking for it. 
It should also be noted that the growth in the lactose solution was 
very slight. An examination of the moss for the enzymes, maltase 
and lactase, would seem pertinent. 
