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XVIII. On the Tubercular Swellings on the Roots of Vicia Faba. 
By H. Marshall Ward, M.A., F.L.S., Fellow of Christ’s College, Cambridge, and 
Professor of Botany in the Forestry School, Royal Indian College, Cooper s Hill. 
Communicated by Professor M. Foster, Sec. R.S. 
Received May 29,—Read June 16, 1887. 
[Plates 32, 33.] 
It has long been known that the roots of the Leguminosse are commonly provided 
with peculiar tubercle-like swellings of various sizes, from that of a mustard-seed to 
that of a hazel-nut, and attention lias been repeatedly directed to them of late years. 
They were observed by Malpighi, wdio seems to have looked on them as of the 
nature of Galls, # and Treviranus regarded them as undeveloped buds, while A. P. 
DeCandolle considered them as diseased structures. Since that time very various 
ideas have been published with respect to them, and as to their origin and relation to 
the roots which bear them. One of the most curious facts about them is that, 
although it is very difficult to find a specimen of our ordinary Leguminosse (Clover, 
Lucerne, Beans, Peas, Vetches, &c.) the roots of which are free from the swellings, 
no one has succeeded in showing that they do any injury to the plant: this has been 
repeatedly employed as an argument against their being due to the influence of any 
parasite. The contrary opinion has gradually gained ground, however, and I am now 
in a position to prove conclusively that it is the correct one. 
The first close investigation of these root-tubercles (as they may be shortly termed) 
is due to Woronin, who, in 1866,t examined in detail the structure and contents of 
the similar swellings which are to be found on nearly every Alder, as well as those on 
the roots of the Lupin. In the cells of the Alder tubercles Woronin found a curious 
little Fungus, which was referred to the genus Schinzia, founded by Naegeli on a 
form which he himself discovered in the roots of Iris\ in 1842. In the cells of the 
tubercles of the Lupin, Woronin found multitudes of minute corpuscles, which he 
took to be Bacteria, or Vibrios, or organisms of that kind. 
Similar swmllings have from time to time been observed on the roots of various 
* ‘Botan. Zeitnng,’ 1874, p. 382; and Sorauer, ‘ Pflanzenkrankbeiten,’ vol. 1, p. 744. 
f ‘Memoires de l’Academie des Sciences de St. Petersbourg,’ vol. 10 (May, 1866). 
X ‘ Linnsea,’ vol. 16, 1842 (Plate xi., figs. 1-10). 
3 z 2 
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