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within still more clearly, and where they are giving an echinulate appearance to the 
bladder within (an appearance adverted to lately by Mr. Berkeley in a letter to the 
Gardeners’ Chronicle) ; L shows the bladder from within the oospore being discharged 
from the oogonium after the manner of Cystopus, with the contained zoospores ; this 
bladder frequently breaks up into dust, as at M, setting the zoospores which are 
at present quiescent free, as at N; two tails shortly appear on these latter bodies, 
and at a certain period of their growth the anterior cilium, or tail, is pushed straight 
out as seen at 0, the posterior tail then quivers with an undulatory movement, and 
the zoospores sail out of the field of the microscope. How long the zoospores live 
it is difficult to say, but probably somewhere between twelve hours and a week ; 
at length they come to rest, as at Pp, when the tails fall into fine dust. Some 
zoospores burst and at once perish, as at Q, whilst others throw out threads of 
mycelium, R, which threads are destined at length to bear the conidiophores of the 
Potato fungus in its new generation. The zoospores thus obtained were planted 
on the foliage, and upon thin slices of Potato supplied from a frame by Mr. Alfred 
Smee. On these materials they at once produced mycelium and small conidio- 
phores, which, without doubt, belonged to Peronospora, but as better results were 
. afterwards obtained from resting-spores similar to 1, fig. 1, the figures are not here 
engraved. 
The Rev. J. E. Vize, Forden Vicarage, Welshpool, a gentleman who has 
made a special study of microscopic fungi, has had some of my living material 
under examination during the past winter and spring, and when the first signs of 
germination showed themselves in my oospores, I wrote him to keep a good look- 
out for results. He wrote me as follows, under date of April 21: ‘‘My idea 
certainly 1s that the oospores are germinating: bottle No. 1 had a thin film on it 
which developed into a lot of mycelium and threads of Peronospora ;” I, too, 
observe the same fact in London. 
Throughout May the habit of the oospores appeared to remarkably change, 
for instead of producing zoospores they protruded a thick and generally jointed 
thread, this thread agreeing exactly in size with average Peronospora infestans 
threads. On May 13 I observed on the preparations treated with expressed juice 
of horse-dung threads similar to the very long branched thread shown at 8, 8, 8, 
fig. 2; these threads were so long that they traversed the entire slide, and I could 
only detect a single septum or joint, and frequently none. 1, U, Vv, are character- 
istic: the latter shows two septa, which is a common condition at this stage of 
growth ; and all three figures show the protoplasm of the oospore coiled up within 
the walls of the latter. w shows an oospore germinating with the antheridium (a) 
attached to the oogonium, and still upon its last year’s thread ; x is a germinating 
oospore with a thread showing the first septum ; and y shows two germinating 
oospores emerging from one oogonium, each thread showing the first septum ; the 
old male organ (antheridium) is still attached to w, x, and y. The figure at z, 
drawn on May 12, is characteristic, and shows three septa ; the specimen was sent 
on to the Rev. M. J. Berkeley, who replied: ‘‘ I found the germinating oospore 
exactly as you figure it. There can be no doubt about the matter.” Mr. Broome, 
W 
