SXXviii PEOCEEDINGS OF THE EOTAL HOETICULTUEAL SOCEETT. 
ever, to call the attention of the committee to some results 
which they had obtained with diseased potatos. Already the 
Hey. J. H. Jellett* had examined the juice, or rather the 
extract, of sound potatos, of the apparently sound part of 
diseased potatos, and of the discoloured part of diseased potatos, 
Ee had found a considerable development of sugar in the white 
part of the diseased tubers. He also determined the amount of nitro¬ 
gen in the dry matter of similar specimens, and found it to be greater 
in that of the apparently sound part of diseased potatos than in 
that of sound potatos, and also greater in the diseased part, but 
not so great as in the apparently sound part. 
At ftothamsted they had experimented rather differently. 
They had determined the nitrogen, and the mineral matter, in the 
soun'd whole tubers, and in the diseased whole tubers ; in the juice 
of the sound potatos, in that of the white part of the diseased 
potatos, and in that of the black part of the diseased potatos. 
They had also determined them in the washed or exhausted solid 
matter, or “mark” of the white part, and of the black part, of 
diseased tubers. 
In accordance with Prof. Jellett’s results they found a higher 
per-centage of nitrogen in the dry substance of the diseased than of, 
the sound potatos; but, calculating the quantity upon the fresh 
tubers, they did not find evidence that there was an actually 
greater amount of nitrogen in the diseased potatos. 
The most interesting point in their results was, however, that 
whilst the juice of the white portion of the diseased potatos con¬ 
tained, approximately, the same amount of nitrogen as that of corre¬ 
sponding sound potatos, the juice of the diseased portion contained 
very much less; in fact, only about one-half or two-thirds as 
much. On the other hand, the washed or exhausted “mark” of 
the white portion contained a very small amount of nitrogen, 
whilst that of the black or diseased portion contained very much 
more; in some cases four or five or more times as much as the 
“ mark ” of the white portion. It was also found that the amount 
of mineral matter was much higher in the juice of the white than 
in that of the diseased portion; but much lower in the “mark” 
of the white than in that of the discoloured portion. It was obvious, 
from these facts, that the juice had suffered exhaustion of much of 
both its nitrogen and its mineral matter in the development of 
* Proceedings of the Boyal Irish Academy, May 22nd, 1876, 
