SIDE LIGHTS ON THE POTATO DISEASE. 
157 
Healthy “ Fluke ” potatoes planted in contact with diseased 
“ King of Ear lies” took the disease badly; the foliage was very 
dark in the spring, showed the disease in the autumn, and at the 
time of digging up the “ Flukes” were diseased right through, 
and the “King of Earlies” abortively sprouting. Both were 
covered with a dense mycelium, and the plants of Volutella 
ciliata (Fr.) were present in all stages of growth both inside 
and outside the tubers, and connected with mycelial threads. 
We also tried some “ Peach” potatoes planted with diseased 
“ King of Earlies.” The foliage again came up intensely dark, 
and showed the disease in autumn ; later on “ King of Earlies ” 
was completely putrid and full of worms. “ Peach,” however, 
was almost free from disease, and what existed was of a very 
superficial character, two tubers only being slightly touched out 
of the entire crop, which was very good. 
We tried healthy “Early Rose” tied to diseased “Kentish 
Early.” The foliage was very late in appearing, but when it 
did appear it was perfectly healthy ; it however soon showed 
signs of disease, and in the autumn “ Kentish Early ” was one 
putrid mass, having made no attempt to germinate, whilst 
“ Early Rose” was half dead and putrid, and the earth sur- 
rounding both potatoes was densely traversed by white mycelial 
threads ; — no crop. 
In conclusion, we tied healthy “Kingsholm Kidney” to 
diseased “ Kentish Early,” sound “Gloucestershire Kidney” to 
affected “ Kentish Early,” and healthy “ Milky White ” to 
diseased “ King of Earlies,” with the effect that the healthy 
plants at once took the disease and were totally destroyed, 
making no apparent effort to germinate, the decomposed por- 
tions being found full of acari and worms. 
We have found as a rule, in our experiments, that the potato- 
skins resisted decomposition to the last, and that the cut sur- 
faces of sound potatoes were the readiest to be affected by the 
corroding influence of the naked plasma present in the diseased 
ones. That some potatoes are, however, able to resist this 
influence for some time is conclusively proved by “ Red-skin 
Flourball ” remaining unaffected for a month. In the autumn 
of 1872 we had a large quantity of diseased potatoes thrown 
into a corner in a heap. By the spring of 1873 the interiors 
had completely rotted away, leaving only the dried skins, appa- 
rently free from disease. These skins sprouted in a healthy 
manner, and gave promise of sound plants, but we had no 
opportunity of planting them. In examining thin slices of 
diseased potatoes under the microscope, we have constantly 
found the starch affected and discoloured, which has not gene- 
rally been acknowledged as a fact ; and we have also been very 
much struck by the abundance of mycelium sometimes pro- 
