290 
THE FLORIST. 
the plant through the medium of rain-water, and thereby affording an 
extra supply of nitrogen or its compounds to the Potato-fungi, which, 
like all other fungi, are known to increase with wonderful rapidity 
when provided with an abundance of this kind of food. Whether this 
hypothesis may prove to be correct in all its bearings we do not under¬ 
take to say ; but, so far as our own observations lead us to form an 
opinion, we consider it the most intelligible inference yet drawn in 
reference to the connexion of thunder-storms with the increased viru¬ 
lence of the disease which takes place after their occurrence. All our 
correspondents inform us of the fact of their crops becoming much worse 
after the late rains, even where sound previously ; but we give a case or 
two which we have witnessed ourselves. A short time before the heavy 
rains which fell in August we walked over four acres of Potatoes in 
company with a friend to whom they belonged; they were the variety 
known as “ Irish Cups,” and we remarked on their luxuriant appear¬ 
ance ; on trying them, the tubers were all sound and healthy. My 
friend saw them the day before the storm, and no trace of disease was 
observable. They were almost inundated for two days by the rain 
which fell, and the third day afterwards showed the disease, which 
progressed with great rapidity and quickly destroyed the crop, which 
has been ploughed up as worthless. An adjoining piece of about two 
acres of “ Regents ” suffered in the same manner, and have been sold 
for \l. per acre. We could cite several other cases of a similar nature, 
if necessary, to prove the almost simultaneous spread of the disease 
which followed these storms. 
The intensity of the malady is greatly increased when the plants grow 
on a damp soil. In our own field, which contains some isolated damp 
spots (but is otherwise quite dry), a much larger proportion of the crop 
is rotten. On such patches not more than one-Wentieth part is 
sound, while on the adjoining land, where the soil is dry, a much less 
proportion is found diseased. As we have not observed so marked a 
difference in former years, when under the same crop, the natural 
coldness of the soil has been increased by the rains to a point fatal to 
the crop, unless the causes named above have a more intensifying action 
on damp soils. 
On examining the crops now being taken up on a variety of soils, the 
best crops in this neighbourhood are being obtained from dry calcareous 
loams, of rather a heavy texture ; on these soils the proportion of 
diseased tubers is comparatively small, but the hot weather of June 
and July had nearly perfected their growth, and they have not suffered 
in the same ratio as the later crops. Next, as regards freedom from 
disease, are the crops on dry sandy loam. Where the land has been 
enriched with farm-yard manure, as we expected, the produce is much 
diseased ; leaf-soil, wood-ashes, and artificial manures are producing 
the cleanest and soundest tubers, other conditions being the same. 
Decidedly the finest crop we have examined was drilled in with 
superphosphate of lime and soot, and a top-dressing of soot applied 
before earthing up the rows; the crop was Regents, and the disease 
made little progress with them, and they continued growing up to a 
late period—long after their neighbours were dried up. Can any of our 
