1893. | Texas Root Rot of Cotton. 17 
In the summer of 1892 I undertook the work again since 
my labors in the south were soon to end and I was very 
anxious to obtain a pure culture of this extremely interesting 
and important organism. I was well supplied with fresh 
material which was being received once or twice each week. ? 
Most of the roots were sent by Mr. R. D. Blackshear, to 
whom I am especially indebted for the patience and care 
manifested in gathering and shipping the specimens. Each 
root was wrapped separately with moist paper retaining a 
small portion of the earth next it, and several such roots then 
bound into a single package. They were usually received 
two days after being removed from the ground. While the 
roots were en route I prepared several large moist chambers in 
the following way: A layer of sand about one-half inch deep 
was placed in the lower vessel and covered with four thick- 
nesses of filter paper. The sand and paper were then well 
moistened with distilled water, the cover placed in position, 
being elevated somewhat from the rim of the lower vessel by 
two tufts of moist cotton to allow free movement of air and 
steam, this precaution being necessary to avoid breaking the 
glass while being sterilized. The moist chambers were then 
piled in a large dry oven, the temperature of which was raised 
to 140°C. for an hour or two on two successive days. The 
filter paper was first perforated in several places to prevent its 
being raised from the sand by steam. When sterilization 
was complete the tufts of cotton separating bottom and cover 
were removed. 
On receipt of the roots they were carefully unwrapped, the 
earth removed, the roots rinsed with distilled water, cut in 
sections about 5™ long and placed horizontally on the filter 
paper, four or five sections in each moist chamber. 
In two or three days the strands of the Ozonium could be 
seen growing out over the filter paper for 4™ to 6™ away from 
the root. The strands were examined microscopically to de- 
termine the fungus. Sterilized glass slides were now placed at 
the advancing edge of the strand or weft, and upon these 
were placed small sections of cotton roots, which had been 
previously boiled and then steamed for several hours for three 
or four successive days, to thoroughly sterilize them. Sec- 
tions of such roots about 3°" long were placed, with the aid 
*Through the kindness of Prof. Geo. W. Curtis, Dir. of the Agri. Exp. Sta, , | 
M fo 
r. R. D. Blackshear, Navasota, and Mr. W. H. Farley, Hutto, Texas. 
2—-Vol. XVIi.—No.3,. > 
4 
