TUBERCULAR SWELLINGS ON THE ROOTS' OF VICIA FABA. 
541 
genera, and in all parts of the world, as the examination of herbaria shows : on 
heights and in valleys, in poor soil and in good land, wet or dry, they may almost 
invariably be met with. 
Eriksson found that in Faba vulgaris the young tubercle-like swellings arise in 
the cortical layer of the main root, or of a lateral rootlet, and without reference to the 
position or age of other parts. Although the development of the tubercle resembles 
that of a rootlet in many respects, its origin has no constant relation to the xylem 
and phloem strands—sometimes it begins to develop between the strands, or opposite 
one or other of them. Although the pericambium joins in the development sub¬ 
sequently, the origin of the swelling is outside the plerome cylinder, and is first 
evinced by active irregular divisions of the innermost cells of the periblem. 
Eriksson observed that the inner cells of the swelling contained the vibrio-like 
bodies described by Woronin : in the outer part of the swelling he occasionally 
noticed Fungus hyphse proceeding radially inwards from cell to cell, and becoming 
branched and finer as they go inwards. Eriksson saw no hyphse in the cells con¬ 
taining the vibrio-like bodies : he noticed also that the latter are not always simple 
rod-like bodies, but oftener forked, &c. He left it open whether any connection 
exists between the hyphse and the vibrio-like bodies. 
In 1878 Kny asserted* that the tubercular swellings on the roots of Leguminosse 
do not appear on plants cultivated in nutritive fluids, and expressed the opinion that 
this was because some parasite which causes the tubercles is absent from the fluids— 
in fact, is evidence in favour of the parasitic nature of the swellings. Kny also 
stated that he found a plasmocliitm in the dividing cells of the tubercles, especially in 
Cicer: he states that the parasitic plasm odium can be followed from cell to cell in the 
form of delicate, sparsely branched strands. Where they traverse the dividing 
cellulose-walls the plasmodial strands are slightly thickened ( loc . cit., p. 55). 
Then followed the Paper by Frank,! in which he confirmed and extended 
Eriksson’s statements as to the ubiquity of the swellings on the roots. Frank states 
that the greatest care is necessary to prevent the development of the tubercles, that 
they occasionally occur on water-cultures as well as on roots in any soil. They did 
not appear on roots in soil which had been heated, though every plant in soil not so 
treated had them. Frank concluded that the roots are infected from outside by a 
“ germ ” which must be as ubiquitous as the germs of putrefactive and fermentative 
organisms. 
In the cells of the swellings there are always;}; two elements to be found, (l) fine 
hyphse running across the lumina of the cells and through their walls, (2) minute 
cell-like corpuscles suspended in the protoplasm of the cell as in an emulsion. 
That the hyphse are the same as Kny’s plasmodial strands is almost certain, and 
* ‘ Sitzungsber. cl. Botan. Vereins cl. Prov. Brandenburg,’ 1878 (April 26), p. 55. 
t ‘ Botan. Zeitung,’ 1879 (Nos. 24 and 25). 
X Except in those of the Lupin, p. 396, loc. cit. 
