TUBERCULAR SWELLINGS ON THE ROOTS OF YICIA FABA. 
551 
cultures, and even close to where a hypha enters the root-hair. However, the whole 
of this matter is as yet too uncertain for me to say more than that it seems a point 
well worth investigation to determine whether the gemmules will go on budding in 
the soil or on root-hairs. It may, perhaps, be permitted to make another suggestion 
here. Even if, as is usually accepted, the protoplasm of the root-hairs of plants 
cultivated in nutritive solutions—and, if so, presumably of plants in soil—is confined 
to the interior of the cell-walls, these cell-walls are very thin and delicate. There 
are facts which seem to support the view that the germinal hypha starts its course at 
the root-hairs for this reason, and it is not impossible that the gemmules will only 
germinate on the root-hairs of the host-plants. At any rate, I never find them 
elsewhere. 
It is a well-known and very popular view that the Leguminosse enrich the soil in 
nitrogenous substances. There is no doubt that the plants of this natural order 
contain abundance of nitrogenous substances, and it is a fact that the roots of our 
ordinary field and garden Papilionacese go deep, and thus bring up nitrogenous 
compounds from below to enrich the surface soil when the plants are turned into 
it by the spade or plough. It is also unquestionable that the root-tubercles which 
have been described above are extraordinarily rich in nitrogenous substances. Apart 
from the evidence already given, analyses of the tubercles of the Lupin show an 
enormous excess of proteicls as compared with the other parts of the roots,* and, since 
these tubercles are aptt to be on the upper portions of the root, it is not improbable 
that these circumstances have contributed to the views so favourable among agricul¬ 
turists. Of course there may be more in this matter than meets the eye, if future 
investigations demonstrate that the gemmules can live as saprophytes or ferment- 
organisms in the soil outside the plant. 
The above results were already on paper, and had been shown to friends, vdien the 
‘ Berichte cler Deutschen Botanischen Gesellschaft/ Heft 2, 1887, came to hand, con¬ 
taining a paper by Tschirch on the root-tubercles of the Leguminosse.J The Paper is 
somewhat long, and not always clear, but, since it contains important and sweeping 
statements as to the biological significance of these root-tubercles, it will be necessary 
to devote some time to its examination. Tschirch has investigated chiefly the anatomy 
of the tubercles on the roots of the Lupine and Robinict, and expressly states that 
the research was undertaken at an unfavourable season (October to December), a 
statement which makes it the more surprising that his generalisations should be so 
sweeping in character. He does not seem to have examined Vicia Fab a parti¬ 
cularly, and the following criticisms must be regarded as bearing only on the points 
common to Vicia Faba and other Leguminosse; these are no doubt numerous, but it 
* Troschke, cited by Sorauer, ‘ Pflanzenkrankheiten,’ vol. 1, p. 746. 
t Not necessarily so, as my cultures prove. 
J ‘Beitrage zur Kenntniss der Wurzel-Knollchen der Leguminosen, (1),’pp. 58-98. The same also 
contains a paper by Frank, advocating similar views to those of Brunchorst and Tschirch. 
