190 BOGANICAL GAZETTE [wane 
pletely restored to health by tillage anda judicious applicatios | 
of nitrate of soda. I would direct the attention of every vegetabk 
pathologist to the words in which Professor Bailey summarim 
one of his bulletins on the care of orchards, and to the ordered 
the terms which he uses, ‘Till, feed, prune, spray.” I haw 
outlined the steps which the vegetable pathologist must takes 
order to secure a trustworthy diagnosis. Having learned to de 
tinguish a morbid condition through a working acquaintancesti 
with normal physiology and anatomy, he must determine th 
final cause of disease; by careful investigation he must deci 
whether it is parasitic or otherwise, and, if so, in what degre; 
and he must determine whether the attack of the parasite ® 
immediate, or superinduced by the local destruction of tissues 
by the general debility of the plant. 
One very important question remains to be considered, Vi 
When and how the parasite, if such it be, secures entrance ® 
the host and is thence disseminated. Upon the answer to ths | 
question depends in great measure the whole philosophy of e 
ventive treatment. One method of determining the mati® — 
of course, the careful study of the life history of the fungus . 
question. If it be known, with a reasonable degree of certaitt . 
that a certain pathogenic fungus depends largely up®? 
summer-spores for its dissemination, we naturally recom’ 
preventive treatment with fungicides; if it is @ Pf 
mycelium to which the fungus owes its continuous vitality, | 
Prepared to advise pruning. If it is ascertained that shrongt : 
Spores, seemingly delicate, are enabled to pass uninjured th ee 
an animal’s digestive tract, the manure heap ce : 
attention ; and if careful research in the field and the or ’ 
is at length rewarded by the discovery of resistant spor 10 a 
duced during the winter in or upon the refuse of a dise clea 
we very properly lay the utmost stress upon 4 thoroug? , 
ing up and destruction of all such refuse. A knowledge® 
facts connected with parasitic fungi is absolutely ot | 
wea ‘ 
any intelligent application of preventive measures o : 
not value too highly such researches as those of nie ¢ 
“potato-scab,” or of Aderhold upon the ascosporic 10 = 
