278 
On the Cultivated Potato. 
M. Shirreff * that not a single healthy plant of any sort of potato 
that yields berries, and which was in culture twenty years ago, 
that is before 1849, can now be produced. Varieties show failure 
in the ratio of their remoteness from the parent stock ; root propa- 
gation of varieties causing degeneration. Lawson, according to 
Darwin,! gives for the year 1851 a list of 175 varieties then grown 
in Britain ; he observes, the valuable and selected parts of all 
cultivated productions present the greatest amount of modifica- 
tion, the tubers especially are wonderfully diverse ; this great 
authority holds that disease in plants is hereditary. Curl, dry 
and wet rot. Sir Harry Thompson says, are the same disease ; 
the taint is a virulent form of dry rot ; a severe type of curl 
prevailed from 1831 to 1837, it disappeared in that year, but 
appeared again in 1838 and was the immediate forerunner of 
the potato disease of 1845. The taint kills the sets; they decay, 
there is a wet, black, soapy putrescence — or there is a dry white 
mouldy decay, or it may be a mixture of rot, wet and dry. The 
fourth volume of this ' Journal,' 1844, contains a melancholy 
account of the Bobbin-joan ; J the germs abort, and become little 
buttons, not leaves, a disease of thirty years' standing, wholesale 
abortions, it is said, from exhausted vitality. The ' Journal ' 
contains further an exhaustive illustrative catalogue of the 
insects which affect the potato-crops § — plant-lice, plant-bugs, 
frog-flies, caterpillars, crane-flies, wire-worms, millepedes, mites, 
beetles, flies, and others ; some prey on the leaves, some on the 
tuber. Insects during one hundred years have been constantly 
charged in all visitations as the destructive agents. This theory, 
as might be expected, the learned author of the paper, in 
common with experts at home and abroad, absolutely repudiates ; 
these entomological visitations he treats as effects due to atmos- 
pheric and other remote causes. Happily the all-devouring 
Colorado beetle || is as yet a stranger. Historically we have 
them continuously forced upoa our attention : — curl, taint, scab, 
Bobbin-joan, dry rot, wet rot, lice, bugs, flies, caterpillars, 
worms, mites, beetles, fungi, and other innumerable pests. When 
nature. Pandora-like, stands with open box from which, without 
leaving a visible hope at the bottom, all these evils and distempers 
disperse themselves over the world ; well may the practical man 
exclaim " goodness gracious ! is the healthy and duly cultivated 
* 'Rural Cyclopedia:' John N. Wilson, 1849, Art. "Potato," to the date a com- 
prehensive and can ful monograph, corresponds witli and confirms my own read- 
ing : I saw it for the first time lust smnmer. Lib. R. A. S. E. 
t Darwin, ' Animals and Plants under Domestication,' vol. ii. p. 330, which sec. 
J '.Lnirnal,' R. A. S. E., 1S14, p. 14. 
§ ' Journal,' R. A. S. E., vol. x. p. 70. John Curtis, F.L.S., &c. 
II ' Colorado Beetle, Life History.' See ' Journal,' Second Series, vol. xi. 
