118 BORTHWICK—WARTY DISEASE OF POTATO. 
micrograph of one of these swellings, shows the presence of the 
resting sporangia of the fungus to the left. Again, in Fig. 3, 
where the haulm forks at the surface of the soil, malformed and 
warty leaves are quite evident. The same thing may also be 
seen at the apax of the stolon to the left of the same figure. 
The parasite, it would seem, is able to obtain a lodgement in 
others parts of the plant than the tubers, and as the resting 
sporangia found in all these tissues are capable of propagating 
the disease, this would suggest the destruction of the whole plant 
by burning as a preventive to the further spread and infection. 
Diseased tubers should upon no account be used as “seed,” 
because the sporangia contained in the infected tubers are as 
much the “seed” of the parasite as the tuber is the “seed” of the 
host, and such material will as surely reproduce the fungus as the 
potato plant. 
The appearance of this disease in Scotland is as unfortunate as 
it is unwelcome, and no doubt new centres of infection will be 
reported from time to time as the disease spreads and becomes 
better known. Preventive measures, to be effective, must be 
adopted by all growers of potatoes ; individual or isolated action 
although productive of some good, may be of no avail in a case 
of this kind, nor in the case of any other threatened epidemic. 
Infectious diseases among animals must be reported in order 
that prompt action may be taken in isolating and stamping out 
the malady before it has had time to spread, and no one will 
question the foresight and wisdom which lead to such regulations; 
but in regard to plants it is to be regretted that there is as yet 
no properly organised system of dealing with an outbreak or a 
threatened outbreak of diseases, although the loss occasioned in 
their case may be as serious as that caused in animals, The 
health of the potato crop in Scotland is of extreme importance 
not only to the country itself, but to other countries to which 
“seed” potatoes are sent; hence no effort should be spared in order 
to stamp out this new and recently introduced enemy to such 
an important food crop. 
