181 
AND LIFE-HISTORY OF ENTYLOMA RANUNCULI. 
The method of infection is simple. The camel-hair pencil (or a clean needle), 
charged with conidia, is lightly placed for a moment in a drop of dew, or of distilled 
water, on a leaf of Ranunculus Ficaria. The sowing is then kept moist, either by 
means of a bell-jar placed over the plant, or by means of a damp-cell kept over the 
drop containing the sowing. 
Precautions were taken to obtain the experimental plants from a distance, and from 
localities where no white spots were found on the leaves ; moreover, I kept uninfected 
plants from the same neighbourhood in the same closed greenhouse, during the 
progress of the observations, as control plants. In all but one or two cases the 
infections succeeded perfectly, and in most cases the infective capacity (if I may so 
term it) of the conidia was most strikingly displayed. 
It was perfectly easy to obtain such preparations as those figured at figs. 29 and 31 
by stripping off the epidermis at the spot where the sowing had been made a few 
(12-24) hours previously; and similar preparations were obtainable any rainy day 
from the wet leaves in the ditch referred to above, especially when the leaf was first 
laid on water for a few hours. As the figures show, the conidia germinate normally, 
and at once proceed to push their germinal hyphse through the wide orifices of the 
stomata; very often the germinal hypha makes coils, and it is usually at least 
sinuous. The unsuccessful tail-like hypha is developed at the opposite end of the 
conidium, as before ; but the formation of the interpolated conidium is very rare—the 
germinal tube at once enters the stoma nearest it. Gf. figs. 23—27 and figs. 29 and 31. 
When examining recently infected leaves, or young leaves from the damp ditch 
which were exposed to all the conditions necessary for infection, I often observed 
delicate little stretches of hyphse lying on the cuticle, and looking like bits of a 
filamentous Schizomycete : two such bits are shown in fig. 29. Moreover, it was a 
by no means uncommon occurrence to see similar filaments on the inside of a stoma 
closely applied to the walls of the guard-cells, and evidently making their way 
inwards. It seems not improbable that these isolated filaments are really pieces of 
the germinal tubes, which have been formed at some distance from the stomata, and 
have become detached by the decay of the exhausted portions of hyphse or spores 
behind them. I have already shown that the protoplasm passes along into the ends 
of the delicate germinal tubes, leaving the empty and exhausted portions behind to 
die off (cf. fig. 24), and it is certainly not impossible that by this means these 
filaments can creep forward, so to speak, to distances greater than the tube full of 
protoplasm can reach—in fact, we may say the germinal tube creeps along by building 
its own ladder behind it. 
Be this as it may, the leaves are easily infected by means of the conidia, and in 
nearly every case a pallid greenish-white spot was found on the infected leaf in from 
13 to 19 days from the sowing : moreover, the spot was always confined to the area 
on which the sowing was made. 
The following list of infections will serve to illustrate this. In each case three 
