for the Growth of Undiseased Potatoes. 
389 
ttacked all the kinds of potatoes, it was only to a small extent, 
n the majority of cases, as was to be expected, the potatoes 
jllowed crops of cereals ; in the localities where the disease 
hiefly prevailed there were oats, but at Exeter the precedin": 
rop was wheat. In one place, South Wales, they followed 
urnips, and here the potatoes suffered considerably from 
isease. As far, then, as these experimental plots throw any 
'ight on the subject, it appears,- — 1, that the oospores of the 
ungus do not exist in the tuber, as has already been fairly 
demonstrated by the many careful investigators who have 
*ailed to discover them in the tubers they have examined for 
'his purpose ; and, 2, that the oospores are not produced in the 
)lants of previous crops. These side lights may help to the 
Iscoverv of the wanting link or links in the history of the 
ungus, but we must look to the labours of the cryptogamic 
)0tanist for satisfactory information, and it is matter of 
ongratulation that the Royal Agricultural Society have been so 
>i lunate as to secure the co-operation of Professor De Bary in 
his work. 
The presence of the disease is ascribed by. many to the use of 
ertain manures. Artificial manures, guano, and farmyard- 
iianure are respectively condemned by different growers, each 
\ithout anv sufficient reason ; while particular manures are put 
oruard as specifics against the disease, as well as advantageous 
o the crop. If the hitherto undetected oospores of the fungi were 
ntroduced to the potato field with the manures, it is obvious 
hat artificial manures from the methods of their production 
nust be entirely free from these bodies. In three localities 
.rtificial manures only were applied to the crops, but the results 
lo not hold out any hope that in this direction security may be 
)btained. At Exeter 2 cwt. of nitrate of soda, and 3 cwt. of dis- 
olved bones were applied per acre, but a quarter of the late varie- 
ies were diseased. The early potatoes escaped with a smaller 
:)roportion, but this was due to the fact that they had ripened, 
ind the foliage of most of them had completely disappeared 
lefore the disease showed itself in the last week of August. It 
s certain, moreover, that the full extent of the disease was not 
letected at Exeter when the crops were raised, as the day was 
howery, and the tenacious clay of the field in which they grew 
o adhered to the tubers that it was impossible, without washing- 
very potato, to separate completely the diseased from the sound 
ubers. At Kent the only manure employed was half a ton to 
he acre of Odam's Potato Manure, and though the injury here 
vas slight all the varieties as well as the general crop suffered 
rom disease. At Bedfordshire seventy bushels of soot per 
icre were applied, and the crops were almost free from disease. 
