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Bancroft.—Researches on the 
Malva sylvesfris, Circaea lutetiana (Enchanter’s Nightshade), Funkia spp., 
Digitalis purpurea (Foxglove), and Phlox spp. 
Since it attacks such plants as Cucumber, Melon, and Cabbage, the 
fungus is one of economic importance; the assimilating surface of plants 
attacked may be considerably reduced, and further, in the case of Cabbage, 
the disease may render the f heads ’ quite unsaleable. At times the disease 
has taken the form of an epidemic in Cucumber houses in this country. 
When a leaf is attacked small perforations make their appearance ; these 
increase in size and frequently run together so that they eventually become 
large, irregular holes. The largest holes which have been recorded measured 
about three-fourths of an inch. Surrounding each hole there is usually 
a small, brownish area formed of the dead tissues of the leaf; the remaining 
parts appear to be green and healthy. Along with the rest of the tissues 
the smaller veins perish ; the larger veins, however, as a rule remain. It 
is interesting to note that in its progress this disease differs markedly from 
the so-called ‘ leaf-spot ’ diseases ; in the latter the tissues of isolated spots 
are killed and fall away, leaving holes in the leaf, whereas in the former the 
tissues appear to be eaten away and the holes continue to increase in size. 
An examination of the tissues of the leaf bordering on the hole shows that 
the cells are apparently exhausted of their contents and dried ; it might be 
thought that the formation of the holes and their increase in size were due to 
the falling away of these dead cells, but this is apparently not so in this case. 
From the very commencement of the disease a perforation appears, not a dried 
spot from which the dead tissues fall away leaving a hole ; in fact, it seems 
as if the tissues of the leaf are not merely killed but devoured. This mode 
of action is most unusual for a fungus and resembles that of an animal; it 
would point to the occurrence of ferments of the cytase, protease, and 
diastase classes, and it is hoped that further work on the ferments present 
in this parasite will throw some light on its action on the tissues of the 
leaf. 
The mycelium of the fungus is most abundant in that region which is 
in close proximity to the holes ; further away from the holes the tissues con¬ 
tain little or no mycelium. The hyphae run through the cells ; they are 
colourless when young, become darker in colour as they grow older, are 
variously branched, measure about 4 /z in width, and are without haustoria. 
The conidiophores arise from the hyphae in the tissues of the leaf bordering 
on the holes; they are short, lateral branches of the hyphae, are simple, 
almost hyaline, continuous or sparingly septate, and bear at their tips 
branched chains of conidia. The branched chain arises thus :—from the 
tip of the conidiophore three conidia are usually formed ; each of these bears 
two conidia of a second order, and each conidium of the second order can 
bear one or two of a third order of branching, and so on. The conidia are 
hyaline or almost hyaline, continuous, elliptical, and measure 8-9 x 4 \i. 
