404 Proceedings of Boycd Society of EdMurgh. [june 18 , 
Naegeli in 1842, who found that the swellings upon the roots of 
Iris were caused by a parasitic fungus. 
The peculiar nodules upon the roots of various members of the 
Leguminosse have been examined by Malpighi, A. P. De Candolle, 
Woronin, Eriksson, Frank, Kny, Treviranus, H. M. Ward, and 
others ; whilst the roots of many infested species of Cruciferse have 
received special attention from the hands of Dr Woronin (Prings- 
heim, Jalirb. fur Botan.^ vol. xi. p. 548). 
In the present paper, I intend to describe an investigation con- 
cerning the cause of the nodular growths found upon the roots of 
Cucumis saliva. 
I received on August 24, 1887, from Mr E. F. Crocker (a 
market gardener of Ham Green, Bristol), a large number of roots of 
cucumber plants with “peculiar knot-like bodies” upon their 
external surfaces; — and from a quantitative estimation of the 
nitrogen contained in these “ swellings ” and in the roots proper, 
I was at first inclined to believe in the hypothesis of Tschirch 
applying to the outgrowths on Cucumis. It will be remembered 
that in a recent paper, Tschirch {Berichte der Deidsclien Botanisclien 
Gesellschaftj Heft 2, 1887), in describing the root-tubercles found 
in the Leguminosse, stated that most probably they were store- 
houses for nitrogenous compounds, — these compounds being subse- 
quently used up in the ripening of the seed. 
On submitting the nodules, roots, &c., of Cucumis to chemical 
analysis, the following percentages of albuminoids were obtained : — 
I. 
II. 
III. 
Albuminoids in nodules, . . . 20*24 
19*96 
20*51 
„ „ roots (without nodules), 
1*92 
2-00 
2*06 
„ „ stem and leaves. 
3*21 
3*24 
3*30 
Although, as just stated, the analyses 
appeared to 
support 
Tschirch’s idea, it was soon discovered, by a microscopical study of 
these roots, that the nodular growths were due to the life-history of 
a parasitic fungus which was found to belong to the UstilaginesB, or 
the group to which the “ smuts ” are important members. 
The Life-History of Ustilago cucumis. 
1 propose to call this fungus by the generic and specific names of 
Ustilago cucumis, indicating that it belongs to the genus Ustilago, 
