802 * REPORT OF THE CONFERENCE ON GENETICS, 
and expressed himself as feeling that the whole year had been wasted. 
I cheered and encouraged him as best I could and advised him to continue. 
The key to the situation was obtained the next year. Subsequently the 
work was carried out as follows, Mr. Orton receiving great assistance from 
some of the growers, particularly from Mr. Rivers, on whose plantation 
the very resistant “ Rivers Cotton ”’ originated. 
In fields much subject to this disease it was observed that here and 
there a plant came to maturity and bore fruit. The seeds were selected 
from these unusually resistant plants, and the following spring they were 
planted on land subject to the disease. Many of the resultant plants 
contracted the disease, but a considerable proportion remained free from 
it or practically free. Selections this year were made from the most 
resistant plants, having an eye also to obtaining plants with other good 
qualities, such as productivity, shape of boll, length of fibre, &c. The 
same method was pursued the following year. In the course of four 
years plants were obtained with good productivity, good quality of fibre, 
and marked resistance to disease. Such plants stood up and bore a good 
crop on fields where the ordinary cotton made a total failure. The fungus 
was frequently found in the small roots of such plants, but it seemed to 
have lost its destructive power. For some years now the Department has 
sent out quantities of this cotton seed to the growers, and they have also 
quite generally begun to make selections for themselves from resistant 
plants. It is about seven years since this work was begun, and the 
growers now no longer fear this disease. Fields which were abandoned 
are again under cultivation, and the problem appears to be solved. 
Melon.—Mr. Orton has also had charge of the work of obtaining 
resistant varieties of watermelons to replace varieties much subject to a 
soil disease which I was able to demonstrate to be similar to the cotton 
disease, z.e. due to a soil Fusarium. There are large areas in the United 
States (parts of Carolina, Georgia, Florida, and Texas) where this 
watermelon disease has prevailed to such an extent that the growing of 
melons on a commercial scale has been abandoned.* The melon is much 
more subject to this soil disease than the cotton to its disease (i.e. it is 
a less woody and less resistant plant), so that the disease often makes a 
clean sweep of the fields. The plants are attacked in all stages of growth, 
but will often appear to be all right until the melons are half-grown, and 
then suddenly the entire plant wilts and dies within a day or two, and 
the water-conducting system in the stem of the plant is then found to be 
plugged by the fungus, which enters through the root system. I have 
sometimes seen large fields in which there was scarcely a healthy plant. 
The extent of infection in the melon rendered it practically impossible to 
obtain any resistant plants by the process applied to cotton, namely, by 
simple selection. Mr. Orton found, however, that a plant known as the 
“citron ’’ in the United States—that is, a vine T with deeply lobed leaves and 
* In 1899, in the Southern States, a total of 117,551 acres were planted in water- 
melons (U.S. census of 1890). This statement sufficiently shows the importance of 
the crop. 
t Enalish readers must bear in mind that in America all trailing plants are called 
“vines.” What is here meant is the race of hard-fleshed very firm melons which are 
used for the making of preserves. Since these are used for the same purposes as the 
true citron of commerce, they are colloquially known as “ citrons.’’—Ep. 
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