564 
Notes. 
the winter and spring. A spotted tuber may give rise to some healthy 
and some diseased sprouts, according to the tracks of the fungus. 
A curious phenomenon was observed in some potato-plants very 
badly attacked by this disease this summer. In some of the badly 
diseased young shoots, quantities of beautifully developed cubical 
proteid crystals (crystalloids) were observed in the parenchyma of the 
pitch and cortex. It is due to Mr. W. G. P. Ellis to point out that he 
was the first to see these in some sections he was kindly cutting for 
me of this batch of specimens. On going further into the matter 
I find such crystalloids have been seen by Heinricher in the shoots of 
a diseased potato 1 , but he did not give any account of the disease 
itself. 
I find these crystals are not uncommon in the still green bases of 
the petioles of the withered leaves hanging on the diseased shoots, 
though they do not always occur. 
I ascribe their formation to the accumulation of proteids in the 
leaves, while still living and active, from which the passages of trans- 
ference at the nodes of the stem have been cut off by the fungus ; just 
as the eventual withering of the leaves is due to the blocking of their 
water-conduits when all the vessels are stopped up. 
At the same time, the attempts I have made to induce the formation 
of these crystalloids artificially have failed so far. 
Neither ringing, nor ringing combined with destruction 01 the pith 
with a hot skewer — to destroy the internal phloem — has given satis- 
factory results as yet, though the leaves of healthy plants withstand 
this drastic procedure much better than might be supposed. 
Here again I must reserve further particulars for the fuller paper. 
In conclusion, it is evident that the efforts of the potato-grower must 
be directed to the selection of sound sets, and to the careful preparation 
of his ground. I hope to show later that it is a fatal procedure, even 
with sound sprouts, to allow the young shoots to lie in contact with 
raw manures, as it is via wounds and small rotting spots at and near 
the collar that new infections occur. The same arguments apply to 
wet soils and situations, and the disease is particularly apt to increase 
when wet and cold weather supervenes on the early growths. 
H. MARSHALL WARD, Cambridge. 
1 Ber. d. deutsch. bot. Ges., 1891. 
