248 BOTANICAL GAZETTE [MARCH 
power when grown on mineral nutrient agar containing a nitrate and glucose. 
There was no fixation when nitrogen was supplied in the organic form, and 
with a nitrate present but no carbohydrate, the amount of fixation was not 
marked enough to be conclusive. There seemed to be some fixation in the 
latter case, the lesser amount being due, perhaps, to the much decreased growth 
where the carbohydrate was omitted. One species seemed to have the power of 
denitrification as well as nitrogen fixation. The amount of nitrogen fixed by 
the algal species used compared favorably with the amount recorded by other 
investigators as fixed by the nitrogen fixing bacteria. The results recorded 
in this paper are contrary to the generally accepted view as to the ability of 
green plants to make use of free nitrogen. The possibility of green plants 
possessing this power of nitrogen fixation, however, is of such great interest 
both scientifically and economically that the work of WANN should be the 
stimulus for much more work along this same line.—S. V. EATON. 
Variation in stomata and hydathodes.—In a study of the number of 
stomata per sq. mm. upon leaves of Campanula rotundifolia borne upon 
different parts of the same plant and upon the leaves of plants grown under 
different conditions of habitat, Miss Rea‘ found some interesting variations. 
In general there was an increase in number from the lower to the higher position 
of the leaf upon the shoot, and an increase with conditions of increasing dryness. 
Such increase was least upon the under surface of leaves on different portions of 
the stem of the same plant. It is suggested that the increased number upon 
sun shoots compared with those developed in the shade is due to increased 
photosynthesis, although no causal connection is established. It would be 
desirable to know the connection between the size of tht epidermal cells and 
the number of stomata, but this information is not given. Groups of hyda- 
thodes were found on the upper surfaces of all leaves examined, the number 
per leaf decreasing from the base to the apex of the shoots.—G. D. FULLER. 
Water relations of Pinus and Leucadendron.—Following methods devised 
eu 
instituted between transpiration and the rate of water transmission. 
rate of transpiration was higher in Pinus, both per twig and per unit area, than 
in Leucadendron, as was also the ratio of transpiration to transmission. From 
the data obtained it would seem that the wood of Pinus is capable of trans- 
mitting a limited amount of water which it utilizes with a very small margin 
of surplus.—G. D. FULLER. 
™ Rea, Marcaret W., Stomata and hydathodes in Campanula rotundifolia 
L., and their relation to ieichenniing: New Phytol. 20:56-72. 921 
9 AITKEN, R. D., The water relations of the pine (Pinus pinaster) and the silver 
tree ‘Leucadendron sein’ Trans. Roy. Soc. So. Africa 10:5-19. 1921. 
