540 
PROFESSOR H. MARSHALL WARD ON THE 
other plants, those on Cyperus flavescens and Juncus bufonius* * * § ** being the best-known. 
Those of' Juncus are especially interesting, because they have lately been shown to 
contain a parasitic Fungus belonging to the group Ustilaginese.f The swellings on 
the roots of Orobccnche also contain a Fungus, referred to by Schacht| : those of 
Sonneratia and Taxodium are not (so far as I can discover) so well known; although 
there is still so much that is doubtful about them, they probably differ in character 
from the others* 
Mention may be made of the fungi long known in the roots of Orchids, but not 
causing tubercles of the kind referred to : some of them at least are now known to 
belong to the genus Nectria .§ These, and other root-fungi, need be no further 
regarded here, however ; nor is it necessary to speak of other root-tubercles, jj 
In 1878 Woronin published his celebrated memoir on Plcismodiopliora Brussicce , r 
a Myxornycete which causes the long-known hypertrophies (Club-foot, Hanbury, 
Fingers and Toes) on the roots of various species of Cruciferse. It is important to 
notice this paper, because it seemed to throw an entirely new light on the general 
question as to the causes of swellings on roots, and at any rate it was the forerunner 
of several suggestions. 
Confining our attention to the swellings or tubercles on the roots of the Legu- 
minosse (and particularly the Papilionaceae), as already stated, their more exact study 
was initiated by Woronin, who examined those of the Lupin, and found the cells in 
the interior of the swellings filled with a slimy colourless matrix in which Bacteria-like 
granules were embedded : the “ Bacteria ” were found to increase, in proportion to 
the rest of the matrix, as the section receded from the growing apex of the swelling. 
In a paragraph at the end of his paper on Plasmodiophora , # * in 1878, Woronin 
practically retracted his previous opinion that the above granular bodies are really 
Bacteria or Vibrios, and regarded it as highly probable that a Plasmodiophora , or 
similar parasite, would be found to be the exciting agent. 
Meanwhile, in 1874, Eriksson had published a masterly investigation of the occur¬ 
rence, form, structure, and growth of the swellings on the roots of Leguminosae.tt 
Their forms differ on the roots of different species, but are remarkably constant in the 
case of any one species. Perhaps the most striking fact about them is their ubiquity, 
confirmed subsequently by Frank.|^ They are found on the roots of species of all the 
* Magnus in ‘ Hedwigia,’ 1878. 
t C. Weber, ‘ Botan. Zeitung,’ 1884 (No. 24). 
J Reference in Frank, ‘ Krankheiten der Pflanzen,’ p. 653. 
§ Wahrlich in ‘ Botan. Zeitung,’ 1886 (Nos. 28, 29). 
| Such as those in which nematoid worms, &c., are found, for instance, and the gall-structures 
caused by various insects. 
‘ Pringsheim, Jahrb. f. Botan.,’ vol. 11, 1878, p. 548. 
** Loc. cit., p. 571. 
tt “ Studier ofver Leguminosernas rotknolar,” Lund, 1874. See ‘ Botan. Zeitung,’ 1S74, p. 381. 
H ‘ Botan. Zeitung,’ 1879 (Nos. 24, 25). 
