1904] BRIEFER ARTICLES 67 
the name is a synonym of Aecidium O-xalidis Thuem., judging from the 
brief description in Saccardo’s Syll. 11:21 5, and from the fact that corn 
is grown in the region where the fungus was found. 
1893. Collected on Oxalis stricta L. at Lincoln, Neb., by the Botanical 
Seminar (Bot. Survey Neb. 3:10). I have not seen the collection. 
1894, 1899. The herbarium of the writer also contains a collection 
made by Mr. T. A. Williams on July 13, 1894, at Brookings, S. D.. and 
one by Mr. E. Bartholomew on June 5, 1899, in Rooks county, Kan., both 
on Oxalis stricta L., of which there is no published record. 
Summing up the evidence, the writer believes that all the above col- 
lections can be placed with much confidence under Puccinia Sorghi Schw., 
as representing the aecidial stage of the fungus. It would be interesting to 
discuss the change in views which this discovery of the aecidium must 
produce regarding the propagation and dissemination of corn rust, but 
that can better be left for another occasion.—J. C. ArTHuR, Purdue Uni- 
versity, Lafayette, Ind. 
AN EXPERIMENT ON THE RELATION OF SOIL PHYSICS TO 
PLANT GROWTH. 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY. LX. 
(WITH THREE FIGURES) 
In studies of the relation of soils to vegetational distribution in Michi-° 
gan,‘ one of the authors found reason to believe that the nature of the 
vegetation covering any upland area of that region has been determined 
by the amount of water present in the surface layers of the soil. Further- 
More, it was pointed out that, with the exception of swamp margins, the 
amount of water thus present is dependent upon the physical nature of the 
soil, especially upon its water-retaining or capillary power, which, in turn, 
is largely dependent upon the size of the soil particles.’ The physics of 
this Proposition, together with the literature thereon, is discussed in a 
paper about to appear in the Annual Report of the Michigan Board of 
Geological Survey for 1903. It will be necessary to state here only the 
general fact that the smaller the particles of a soil, the greater will be its 
Water-retaining power, and the larger the particles, the smaller this prop- 
erty. Also, the greater the retaining power, the greater will be the power 
to lift water from a lower level. Thus, clay soils have a great power of 
* Livincston, B. E., The distribution of the plant societies of Kent county, 
Michigan. Ann. Report Michigan Board of Geol. Survey, 1gor. 
The distribution of the upland plant societies of Kent county, Michigan. Bor. 
Gaz. 35: 36-55. 1903. 
