New York AGRICULTURAL EXPERIMENT STATION. 67 
Accordingly the fact that P. campestris, the cause of black rot, 
was present in these seed cabbage plants at blooming time is 
settled beyond question. The observations of each succeeding 
season show that while the amount of black rot present varies 
considerably with different seasons the disease is never absent 
from any considerable area. 
DISEASE GERMS ON THE SEED. 
ISOLATION OF GERM FROM SEED PLANTS. 
In June, 1900, we selected and marked four seed-bearing plants 
in the fields near Cutchogue, which were affected with black rot. 
When the seed was ripe the plants were collected by W. A. Fleet, 
inclosed separately in large paper bags and expressed to us. 
Each plant was threshed separately and a small portion of the 
seed soaked in sterile water. Cultures were made from this 
water and small portions of it were also injected into young 
healthy cabbage plants in the greenhouse with the usual pre- 
cautions to prevent the entrance of germs from other souces. 
The amount of water which it is possible to inject into growing 
tissue is small and the production of disease in six out of twelve 
experimental plants is surprising. These results demonstrated 
the presence of P. campestris on the seed of three of the four 
seed plants examined. 
The cultures made from the same water which was used in the 
direct inoculation of the young plants showed the presence of 
P. campestris in the case of three of the seed plants. That the 
colonies were really P. campestris was settled by inoculation with 
all necessary precaution into healthy young plants in the green- 
house. Black rot was produced by the use of pure cultures derived 
from the seed of these three different seed plants. : 
On comparing the results from these two methods of testing 
the infectiousness of the seed it was seen that the germs had been 
isolated by cultures from the seed of the plant which had failed 
to show results from the direct inoculation. Accordingly, we have 
a complete demonstration that the germs of black rot were present 
on the seed of all four of these diseased cabbage seed plants 
at the time of harvesting. 
INTERPRETATION OF THESE RESULTS. 
Concerning any experimental work it is always proper to 
consider in how far the conditions of the experiment have deviated 
