TUBERCULAR SWELLINGS ON THE ROOTS OF VIOIA FABA. 
561 
Fig. 9. A portion .of the last figure still more in detail, and showing the curious 
trumpefc-shaped widenings where the hyphse pass through the cell-walls. 
One branch of the main hypha is attached to the nucleus n of one of the 
cells—this is not uncommon. The first branching of the main hypha 
clearly takes place in the cell-wall. The further branchings are not clear, 
because the course of the hyphse varies in different planes. J/4. 
PLATE 33. 
Fig. 9a. A preparation similar to fig. 9, but showing a much younger stage of the 
development of the tubercle. The infecting hypha is crossing the cortex 
from cell to cell: soon after leaving the root-hair, it branches, the branch 
soon running in the cell-wall. The cells traversed by the hypha are 
hypertrophied. The young tubercle is arising by meristematic division of 
the innermost cortical cells opposite the entering tip of the infecting 
hypha, which is in contact with a nucleus. (E.) 
Fig. 10. Part of the central tissue of a young tubercle (near the apex in fig. 3), 
showing the characters of the hyphse, and their branching in the cells. 
The haustorium-like branch in the centre is very characteristic. E/4. 
Fig. 11. Similar preparation from nearer the apex of the tubercle. The hyphse are 
thicker, and their course more direct. This and the last figure from 
preparations treated with very dilute ammonia. E/4. 
Fig. 12. Similar preparation (fresh) from the lower part of the central tissue of the 
tubercle, corresponding to the part shaded dark in fig. 3. The protoplasm 
of the cells is nearly filled, with the budding gemmules, and has become 
vacuolated and plasmodium-like, the nucleus being driven to one side. 
Branches of the hyphse are seen in the cells, and dense tufts of budding 
gemmules can be seen shining through the matrix (e.g., the lower cell) 
in some cases : in others everything is obscured by the dense matrix. 
Starch often accumulates in the cells at this stage, and the nucleus in 
some cells undergoes a sort of fatty degeneration. (J/4.) 
Fig. 13. Hypha traced down the root-hair into the cortex. It takes origin from 
a brilliant granule—presumably one of the gemmules. From a water- 
culture the root of which was infected by a section from a tubercle of 
the preceding year. The remainder of the course of the hypha is clear 
from figs. 7, 8, 9, 10, 11, 12. The hypha in the cortex subsequently 
turns yellow, and shrivels, and only remote traces are to be found in older 
tubercles. J/4. 
Fig. 13a. Further preparations, resembling that from which fig. 13 was drawn. The 
MDCCCLXXXVII.—B. 4 C 
