AND LIFE-HISTORY OF ENTYLOMA RANUNCULI. 
179 
In fig. 24 are shown other conidia germinating in the same way, under the same 
conditions; the slight variations in detail do not affect the general conformity to the 
above type. It frequently happens that two conidia “ copulate ” after they have 
formed the secondary conidia, or during the development of the latter (fig. 25). This 
often occurs when the conidia are numerous, but by no means always ; the after¬ 
effects of such copulations, if they exist, do not manifest themselves clearly in the 
further fate of the secondary conidia ; they appear to behave exactly as if no copula¬ 
tion had occurred. 
There is a small point of some interest to be noticed here. It has already been 
stated that the cellulose wall of the conidium is exceedingly delicate; it results 
thence that when the conidium is deprived of its protoplasmic contents the remaining 
empty shell is barely visible, and easily overlooked, and the same is true of empty 
portions of hyphae. It often happens, therefore, that such specimens as those in 
fig. 24 (n and r) are not at first sight quite intelligible, until more careful search 
results in the discovery that the empty conidia, &c., are still attached ; in other cases, 
however, the remains of the conidia become destroyed (e.g., by bacteria, &c.), and the 
delicate hyphae containing the protoplasm persist alone. I have excellent reasons for 
believing that such hyphse are not necessarily dead, and that the presence of certain 
fine hyphse on the leaves is to be explained as above. 
First, however, it will be advisable to see what occurs when the conidia are ger¬ 
minating in a drop of water on the leaf of the living Ranunculus, and where the 
increased supply of oxygen may be one of several causes for the fact stated above—- 
that the conidia germinate more rapidly. 
In figs. 26 and 27 are shown several specimens of germinating conidia, which had 
been sown in drops of dew on the living leaf, the plant being kept in a cool green¬ 
house under a glass bell-jar. It is at once noticeable that several of the conidia have 
proceeded at once to the development of the germinal hyphse without the preliminary 
formation of the secondary conidia; the germinal tubes are thicker and stronger than 
is the case with sowings in pure water on glass. Here and there a case occurs (fig. 27) 
where the secondary conidium is interpolated as it were, but this at once proceeds to 
develope the germinal mycelium. Of course, the specimens figured are such as have 
not sent their hyphse through a stoma; very many of them would do so about the 
second or third day after sowing, as shown in figs. 29 and 31. 
It is now necessary to return to the mycelium in the intercellular spaces of the 
mesophyll of the leaf. It is observed in all cases where the white spots are fairly 
advanced, and wherever the conidia are developed in abundance on the exterior, that 
numerous spherical resting-spores exist among the closely weaved branching hyphae. 
Thin sections and careful examination show further that these resting-spores are 
formed in the course of the hyphae themselves as local dilations, or, more rarely 
perhaps, at the ends of branches which may be very short (figs. 9, 10, 17). It is 
possible to macerate or tease out specimens showing all the chief stages of develop- 
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