AND LIFE-HISTORY OF ENTYLOMA RANUNCULI. 
177 
protoplasm in the hyphse. If the sections are made through somewhat more advanced 
spots, the following additional peculiarities are noticeable (fig. 11). The mycelium 
has increased, and now sends branches into the lacunae beneath the stomata. These 
branches fill up the interspace, and at length project through the orifices of the 
stomata in dense tufts or pencils (figs. 2, 6, and 11). The hyphse are also seen to be 
mingled with numerous small spherical bodies-—the resting-spores of the fungus. 
Subsequently the number of these spores increases enormously, until, in old spots, 
every nook and cranny between the cells is packed with them. Meanwhile, the 
pencils of hyphse projecting to the exterior have produced innumerable colourless 
conidia from their free ends (figs. 3, 4, 5, 12, 13). It is these tufts and conidia which 
give the white powdery appearance to the spots. 
Having thus given a general account of the fungus, I may proceed to describe 
further details as to the intercellular mycelium. It is not difficult to observe that at 
the margins of the spots (in the mesophyll tissue) the tips of the hyphae are extending 
radially in all directions, branching as they do so, and forming septa behind the apices. 
Where the hyphae pass along the wall of a cell, they frequently form flattened short 
branchlets or tufts, closely aj)pressed to the outside of the wall of the cell (fig. 7), 
i.e., on the side bounding the lacunae. These flattened tufts of branchlets are 
strikingly suggestive of haustoria, though they do not obviously pierce the wall. 
The hyphae appear never to be intracellular. In some cases, with the aid of reagents, 
I have convinced myself that the attachment of these haustorium-like branchlets to the 
cell-wall is very close, and cannot help suspecting that either fine threads of proto¬ 
plasm pass out to them from the sac of protoplasm inside, or that they send such 
fine threads through the cellulose ; it has so far been impossible to place this beyond 
doubt, however. Although the hyphse do not penetrate into the cavity of the cell, 
they can pass in the primary cell-wall (the middle lamella), and so force their way 
between two contiguous cells. Good sections show this distinctly, though, owing to 
the delicacy of the hyphse, they are not easy to obtain. Moreover, as will appear 
clearer shortly, the tips of the hyphse can make their way to the exterior between 
contiguous cells of the epidermis (figs, 11 and 14). 
Following those hyphse the tips of which protrude through the stomata, their ends 
are found to give rise to delicate colourless conidia by abstriction. Taking a given 
hypha, it grows out into the damp air or water, and its tip swells up slightly into an 
ovoid body which may lengthen considerably or not before it is separated off as a very 
delicate colourless conidium, with an extremely thin cell-wall and finely granular 
and vacuolated protoplasmic contents, in which minute brilliant oil-like drops are 
suspended. 
In some cases, apparently in drier warm weather, the protruding hyphse are 
relatively short, and the conidia ovoid or slightly reniform (fig. 3) ; in other cases, 
apparently in wet weather, and certainly in water (fig. 2), the hyphse may protrude 
twice as far before the conidia are abstricted, and the latter are then longer, more 
MDCCCLXXXYII.—B. 2 A 
