The Potatoe Plague. (a 
for seed,) has been a potatoe grower for thirty years, used 
formerly to send five or six hundred bushels of Tawdon kid- 
neys annually to Selby, where they were used for seed, and 
the produce sent to London. He used to grow two hundred 
bushels to the acre, but now considers fifty bushels a good 
crop; has failed so repeatedly the last five years in growing 
a crop, that this year, 1844, he has none, and believes there 
is but one man in the township who continues to grow the 
kidneys. 
I will now state the chemical facts which appear to me to 
confirm and explain the above-mentioned results of practice. 
It is notorious to potatoe growers that a marked change takes 
place in the quality of the tuber when the stem and leaves 
wither, and that potatoes taken up when the plant is still 
growing, are watery, though a portion of the same plot, if of 
a good sort, and in suitable soil, taken up a few weeks later, 
will be found light and mealy. This is probably owing to the 
deposition of starch in the tuber by the descent of the sap, 
when the growth of the plant has ceased, and is apparently 
analogous to the very similar process described by Liebig as 
taking place in all perennial plants. 
“ All the carbonic acid which the plants,” remarks Liebig, 
speaking of perennial only, “now absorb, is employed for 
the production of nutritive matter for the following year. 
Instead of woody fibre, starch is formed, and is diffused 
through every part of the plant by the autumnal sap.” To 
remove every doubt on the subject, however, I took up por- 
tions of two kinds of potatoes, growing in very different situ- 
ations, and a ripe and unripe sample of each, to an analyzing 
chemist, merely numbering the samples, and requesting to 
know the per centage of starch in each. The result was as 
follows : 
