On the Nature and Causes of the Decay in Potatoes. 545 
known for 20 years. The great prevalence of it is due to the 
singular sunless nature of the latter part of the season all over the 
north of Europe. 
The frosting of potatoes I look upon as producing the same 
disease — only it appears in a different form — just as in grated 
sound potatoes. The frost causes a rupture of the cellular tissue, 
tVie juices become mixed, and if left to itself the potato goes into 
the same state of decay and putridity, accompanied with the 
heightening of colour under the skin, as in the present instance. 
The only difference, in my opinion, is that in the diseased potato 
the decay is first effected by the air in the vascular tissue. 
Of course, w ith these views, believing them as I firmly do, and 
having arrived at them after careful consideration of all the evi- 
dence adduced and opinions given, I entirely reject the idea of a 
degeneracy in the potato, and of the prospect of its becoming ex- 
tinct. Such a view has a foundation in mere idle fears, is unsup- 
ported by the history of the past or the experience of the present, 
and has arisen from that very common feeling of ascribing to 
some mystical and hidden cause that which is either beyond our 
ken, or which we have not yet had the sagacity to discover the 
reason. 
If the views which I have adopted be admitted by you, it be- 
comes a simple matter to explain the principles upon which we 
should proceed in storing and in preserving the potato. The 
disease is a decay of the cellular tissue ; but this, like all other 
kinds of decay, is apt to run into putrefaction. A decaying sub- 
stance passes into the putrefactive state when moisture and an 
elevated temperature aid in accelerating the decay. A perfectly 
dry substance cannot putrefy, although it might undergo a slow 
decay ; and, therefore, dryness is, of all means, the most essential 
to prevent the disease assuming the malignant form. This is the 
more essential as all the potatoes have this year an unusual quan- 
tity of water. It was to remove this injurious excess of water that 
the Irish Commissioners recommended so strongly exposure of 
the potatoes to the action of the sun and air. By this action the 
potatoes were rendered drier and more able to resist the attacks of 
decay. At the same time the light exercised a special action on 
the tuber by calling its dormant into a partially active vitality, 
and thus enabling it more effectually to resist external influences. 
Unfortunately this cannot always be carried to the desired extent, 
because in a few days the starch in the cells begins to be changed 
into a green waxy substance, and acrid matters are formed in the 
potato which render it unfit for food. In this country there is 
scarcely a necessity for referring to this first operation after digging, 
but unfortunately in Ireland even yet potatoes remain in the 
ground in many cases of small holdings. In one word, the whole 
