SIDE LIGHTS ON THE POTATO DISEASE. 
By WORTHINGTON G. SMITH, F.L.S. 
8 0 much has been already written about the potato disease, 
that it might reasonably be doubted whether anything 
fresh could, at the present time, be placed on record. It is 
undeniably true that nearly all our knowledge of facts has 
been published over and over again, and it must be confessed 
that these facts have been added but little to since their 
original publication by Berkeley, Montagne, De Bary and 
others ; but at the same time many side lights have been 
recently thrown on the subject of the potato disease by analo- 
gues found amongst other fungi, and by actual experiment. 
Observation and experiment have, without doubt, been greatly 
stimulated by the active measures set on foot by the Royal 
Agricultural Society in offering prizes for additional informa- 
tion, and disease-proof varieties ; the effort to elicit a more 
complete knowledge of the potato disease ended in failure, and 
whether the more recent action in regard to “disease-proof” 
varieties will terminate in the same manner time can only 
show. Few subjects have been more written about by incom- 
petent persons than the potato disease, and many hundreds of 
published essays (including, perhaps, the ninety submitted in 
competition for Lord Cathcart’s prize) are of little value ; 
the horticultural press for the last thirty years has teemed 
with communications of the most worthless character on this 
vexed subject in letters which have pointed to conclusions in 
every direction but the right one ; the deductions and results 
of one writer being invariably flatly contradicted or nullified 
by the experiments and conclusions of another. The history of 
the first appearance of the potato disease has been ably written 
by Berkeley in the first volume of the “ Journal of the Royal 
Horticultural Society,” and this history has been reproduced in 
so many different forms and places, that we think it better to 
pass it over at once with the mere reference to its position. 
A very precise and clear account of the disease itself from a 
scientific point of view — and one embracing all our most 
