122 The Fotato Fungus. By Worthington G. Smith. 
under tlie necessity of dividing the material, and keeping a constant 
look-out for results under different conditions. With this ohject in 
view, therefore, I kept some of the bodies moist in pure water, 
others in diluted expressed juice of horse-dung, others in expressed 
juice of fresh Potato leaves, others upon extremely thin slices of 
Potato and on crushed Potato mash, others in saccharine fluid, 
others in nitrogen gas, some between pieces of glass kept constantly 
moist, some upon broken tile (also kept constantly moist), and some 
upon Potato leaves as they grew upon the living plant. Besides 
this, I have had a quarter of a hundred of slices, kept damp, and 
under examination every day (almost night and day) for the last 
three months. All these preparations I have kept constantly and 
uniformly moist under darkened bell-glasses, for darkness inva- 
riably assists the growth of spores of all sorts. 
The first new fact worthy of note is this : many of the resting 
spores grew in size during nine months of their rest to twice their 
original diameter, or about four times their original bulk, and 
their aspect gradually changed from almost smooth, semi-traDS- 
parent bladders to brown, more or less rough and warted or 
echinulate spheres. These latter brown, mature bodies were 
quite the same in character with those so sparingly seen last 
June and July. How they arose last year no one saw, but pro- 
bably the wet weather of the early summer caused their appear- 
ance. It does not follow,, because the resting spores have taken a 
year to artificially mature with me, that therefore they always take 
a year to ripen ; it is quite possible that, in a state of nature and 
under different conditions, they may mature rapidly. At any rate, 
two sorts of bodies were seen together last year, transparent smooth 
bodies, and rough brown ones. I considered them to be different 
states of the same resting spores, and subsequent facts have proved 
my supposition to be quite correct. 
The top row of illustrations on Plate CLI. shows characteristic 
conditions of the almost mature reproductive bodies as drawn in 
April last. At A is seen the oospore (or resting spore) within 
the oogonium (bladder which holds the resting spore), at B may 
be seen two resting spores within one oogonium, and at C three 
resting spores within one oogonium, whilst at D is shown a double 
oogonium — two oogonia coalesced, and each oogonium containing 
a resting spore. 
At the end of April and beginning of May last I began to see 
the first signs of germination, and at this time many of the oospores 
proved efi'ete ; the oogonium cracked at E, or became broken into 
atoms, as at F, discharging a bladder, as at G, which perished in 
fine dust, as at H. 
As the month of May progressed many of the resting spores 
