175 
Characters of the fungus .—The spores are oblong, usually rather sharply 
pointed at the base, often rounded at both ends, with a broad shallow con¬ 
striction in the middle, nearly cylindrical or distinctly curved, some¬ 
times u binucleate.” They vary greatly in size from 4.5 to 9//in diam¬ 
eter by 15 to 20 fj, in length. Where they are produced on green or 
decaying bolls, or other softened parts of the plant the distinct acervuli 
are 100 to 150// in diameter. On the leaves the acervuli are much 
smaller and very rarely in sufficient quantity to give the roseate tint. 
I have found one case of the fungus on a cotyledon of a young plant 
where the color was distinctly produced. The cotyledons, however, are 
much more succulent than the leaves. It had also been raining for 
several days, so that the diseased part could not dry and thus check 
the profuse development of spores. Many of the spores are borne on 
scattered fertile hyphae within the tissues of the leaf, not being collected 
into distinct clusters. As the tissues of the plant become harder by the 
partial drying of the leaf the spores produced are fewer in number and 
borne mainly upon the ends of the setae. 
The setie are olive or dark brown, straight, curved, flexuous, or rarely 
branched. They arise from especial bodies, resembling somewhat an 
imperfect sclerotium, composed of a single dark-brown cell or of a vary¬ 
ing number of dark-brown cells, generally a few. When of several cells 
it is irregular in shape. It is situated within the tissues of the host or 
projects slightly above the surface or lies along between the cells of 
the epidermis. When the body consists of a single cell it is produced 
at the end of a hypha, but is greater in diameter. These single cells 
may increase to the several-celled sclerotia by a process of growth simi¬ 
lar to budding, except that the cells thus formed remain in a closely 
compact body. The end cells of the setae are nearly hyaline. The spores 
borne upon them are often oval, the base being rather sharply pointed. 
The setae vary in length from 100 to 250//. They are usually decid¬ 
edly shorter on the leaves than on the other parts of the plant. They 
are in clusters of 5 to 10, or more. Frequently the clusters are so numer¬ 
ous as to make it appear that the setae are evenly distributed over the 
.substratum. 
Artificial cultures .—A number of artificial cultures were made to trace 
the development of the setae and the peculiar bodies which bear them. 
The nutrient medium in most cases was agar peptone broth and an 
infusion of cotton leaves. Pure cultures were obtained by placing bolls 
on which the spores were jusc beiug produced in a moist chamber. 
When the cluster of spores was well elevated and distinct, not so old 
as to be contaminated with bacteria, with a flamed needle a few spores 
could usually be taken not accompanied by other germs. 
The cultures were made in cells. The spores germinated quite freely 
within 12 to 15 hours, possibly much sooner under favorable conditions. 
At the time of germination, or prior to it, frequently one or two trans¬ 
verse septa are found in the spore, dividing it into two or three cells. 
