284 
On the Cultivated Potato. 
dependency on the happy-go-lucky potato, was a sort of Ireland : 
the treatment there, 1 fancy, must have been natural and un- 
forced ; any way the important fact remains, the only disease 
known arose from some kidney sets imported from England, 
The following remarkable instances of superior vitality came to 
me from widely separated districts and from persons who could 
have had no sort of concert ; in each of two instances the whole 
of the crop in a field failed except in places where corn stacks 
had stood, and there the potatoes grew and prospered ; I infer 
the ground was dry and warm, and hence the superior vitality. 
We are now to consider those scavengers of na;ture, the fungi, 
a class of cellular plants of which, says Darwin, mushrooms, 
toadstools, and moulds are familiar examples. These tyrants- 
of the vegetable kingdom seek organic matter in decay as their 
natural food ; their wind-borne spores or seeds hover and pounce 
like microscopic vultures. The life-history of the fungus or 
mould, which is inseparably connected as cause or effect with 
the potato-disease of 1845, has been studied by that eminent 
scientist, M. de Bary ;* the identity of the fungus Peronospora 
infestans and its association with the disease is, without any 
doubt, ably and clearly manifested, and for this our thanks to 
that learned gentleman are justly due. But what then? for all 
practical purposes, and after eight years' of incubation, any dis~ 
covery in this direction is as barren of tangible fruits as the 
fig-tree of Scripture. M. De Bary observes — and here I am 
sure he carries us all with him — " the best place to turn to for 
further study would be the native land of the potato-plant." f 
All the Peronosporce, says M. de Bary (p. 244), are typical 
parasites in living plants containing chlorophyll ; their com- 
plete development is dependent on their finding the living 
organism with its chemical and physical properties, which will 
afford a suitable host : most species are restricted, they can only 
grow in certain species or groups of species of plants, but not 
in others, a condition of things which holds good for parasites- 
generally. This, says M. de Bary, does not exclude the possi- 
bility of bringing a parasite, by artificial nutriment, more or less- 
forward. Practically to study all the ways of the parasite, 
whilst we are perfectly ignorant of the life-history of the host- 
plant in its native habitat, is certainly to put the cart before 
the horse — if the somewhat overstrained simile may be par- 
doned, it is rather like writing the life-history of the flea that 
* A most excellent account of all tliat was known about tliis fungus, which 
w^as then calUd Botnjtis infi'sfniis, was drawn up by the Kov. M. J. Berkeley in- 
181(1, and pubHshcd in vol. i. of the 'Journal of the Hoiticultural Society,'' 
jjp. 9-34 ; 25 pa;;cs of letterpress and 4 plates containing 30 figures showing the 
lungiis and it.s allies in difl'erint stages. —J. G. B. 
t ' Journal,' 11. A. S. E., vol. xii. 1870. 
