110 
‘The conspicuous maik present on leaves that have been attacked 
for some time, are sed by the secondary increase in the number 
of leaf-cells over a limited area of the surface being resisted by 
the healthy unyielding tissues of the leaf; hence the abnormal 
growth, stimulated by the action of the parasite, assumes the form 
of a blister, being concave on the upper, and convex on the under 
surface of the leaf. When the points of infection are numerous 
on a leaf, the Sie osos distinct blisters grow into each other 
diae their developm ent. The mycelium is very slender, not 
exceeding 2u in hi ERN. sparingly transversely septate, and 
tinged with yellow when seen in the mass. It runs between the 
cells, which finally become e$: Funes and separated from each 
other. ter becoming co ted in clusters between the 
epidermal cells of the convex varices of the blister, on the under 
surface of the leaf, the mycelium ruptures the cuticle and appears 
on the surface of the blister under the form of minute, densely 
crowded clusters of hyphae. When the growth of the parasite is 
very vigorous the hymenium is not infrequently formed on both 
surfaces of the blister. Some of these hyphae run out into long, 
sterile filaments, ite a minutely downy or velvety appearance 
tothe blister, when seen under a lens; the great majority of the 
hyphae, mir rti ere ag short, and produce a single conidium at 
the a - * The nidia are hyaline, or with a tinge of yellow 
when in the. mass, elliptic with somewhat pointed ends, 
sotto slightly constricted at the septum, straight, or sometimes 
very slightly curved, measuring 14-16 x 5-64. It is not unusual 
to find conidia germinating in situ, each cell of the “cae 
producing one slender germ-tube. Mixed with the conidiophore 
are numerous basidia, but these are not sufficiently crowded nd 
compact to form a typical hymenium, the surface of the tuft 
constantly remaining loose in texture, resembling the face of a 
brush rather than a waxy, compact surface. "The basidia are 
subeylindric, and so far as observed, constantly produce ues 
slender, spine-like sterigmata, es ugh t the presence of fou 
daughter nuclei in some preparations of basidia stained with 
iodine would seem to su tieit the probability of four 
sterigmata being found in some instances. The Vei iesus are hyaline, 
5x3. When old, ee tufts of hyphae appear to contract a lit tle, 
thus becoming more isolated and distant from each other, and 
giving the iymestami s a cracked appearance. 
The branches do not appear to be disfigured to the same extent 
as the leaves by the parasite. 
Preventive measures rumen the —— by Dr. Watt 
that the disease *invariably appears on that has not been 
pruned in the autumn," it seems ut pensieri to suggest that 
autumn pruning should be carried out, unless there is so 
strong reason for not doing so. The removal of diseased portions 
before the spores are mature would go far towards preventing a 
recurrence of the rre Such infected parts should be burned, 
and not allowed to remain on the ground. Spraying would not, 
in all probability, be permissible, vut io a solution of potas- 
sium sulphide (one ounce to three gallons of water) would pre- 
vent to a great extent the spread of the dites if applied at the 
