556 REPORT OF THE COMMISSIONER OF AGRICULTURE. 
The fungus begins its attacks as soon as the first leaves are fairly 
formed, and from that time until the close of the season it continues 
its depredations. Our observations have not been sufficiently numer-. 
ous or complete enough to enable us to make any definite statements 
as to the actual injury occasioned by the blight. The vitality and 
assimilating powers of the diseased leaves are more or less affected, 
according to the virulence of the attack, and in severe cases a seri- 
ously diminished crop must necessarily be the result. 
(6) EXTERNAL CHARACTERS. 
If the lower leaves are carefully examined about the time the 
plants are beginning to bloom, one will see, here and there, some of 
them marked with reddish-brown spots, irregular in outline, and 
variously scattered over the leaf surface. The single spots vary 
from 1™™ to 4™™ in diameter, but often several of these run together, 
producing discolored patches of considerable size. The spots are vis- 
ible on both surfaces of the leaves, showing that the tissues through 
their entire thickness are affected. Inashort time the tissues within 
the spots die and turn brown, leaving a dark red, well-marked border 
between the dead and the surrounding healthy tissues. The dead 
centers of the spots become brittle and are easily broken out, so that 
the leaves are often seen full of holes, or more or less ragged and 
torn about their margins. Leaves badly affected soon lose their 
lively green color, turning to a pale, sickly yellow, and finally wither 
and fall from the stalks. 
(c) BOTANICAL CHARACTERS OF THE FUNGUS. 
The Cercospora gossypina which causes the blight is a fungus 
botanically related to the fungus of the Strawberry-leaf Blight, but 
while we are now acquainted with the several stages in the develop- 
ment of the latter (see p. 339), we know only one stage in the former— 
the Cercospora stage—corresponding to the Ramularia stage in 
Spherella fragarie. j 
It is the vegetative portion or plant body of the fungus, growing 
within the tissues of the leaves which occasions the destruction of the 
cells in the latter, producing the external changes noted above. 
After a while there issues from the mycelial threads within, usually 
coming out through the stomata, short, irregular, dark-colored 
‘ branches, upon whose tips the slender, tapering, colorless spores are 
borne. These branches generally issue in tufts or fascicles of three 
or four or more, and the number of spores borne on each varies from 
one to several. The length of the branches as well as that of the 
spores varies greatly, and the number of septa or cross-walls in the 
latter is also variable.* 
As already intimated, the more advanced stages in the life history 
of this Cercospora are unknown, but it doubtless produces spermo- 
gonial and ascosporous forms on the affected leaves after they have 
fallen to the ground. 
What applications or treatments may serve to check or prevent 
the Cotton blight remain to be determined by experiment. It may 
* The characters of the species as given by Cookeare as follows: Epiphylla. Macu- 
lis effusis, indeterminatis, fuscis. Hyphis subfasciculatis, elongatis, fiexuosis, fuscis 
(.12""-,15™"), Sporis elongatis, superne attenuatis, flexuosis, 5-7 septatis, hyalinis 
(Ona -, {mm > 003mm), 
