1911] PRITCHARD—DISSEMINATION OF PUCCINIA 175 
explain such cases. This theory is based chiefly upon the claim 
that rust apparently infects the cereal host. through the seed, 
although its mycelium is not recognizable in the germ by aid of the 
microscope and present cytological technique. KLEBAHN (20), for 
a time at least, supported this view, and even figured the nuclei 
of the fungus while in the mycoplasmic condition. 
The following experiments on the life history of P. graminis 
were made at the North Dakota Agricultural College and Experi- 
ment Station at Fargo, North Dakota, to obtain information which 
would aid in producing a rust epidemic yearly in our wheat breeding 
plots to test the strains selected for rust resistance. This is a 
spring wheat region, where the winters are exceedingly cold and 
consequently winter cereals are not grown. 
The germinating rusted wheat grains were studied at Madison, 
Wisconsin, under the direction of Dr. R. A. HARPER. 
Method 
All the plants used for inoculation, except when otherwise stated, 
were grown in the greenhouse in beds containing 6-8 inches of 
fertile soil. The grass plants were transplanted to pots and placed 
in the greenhouse several weeks before they were used. The 
temperature was kept reasonably cool, and the air fairly moist 
by frequently watering the floor. 
The inoculations were made by first mixing the spores of a 
pustule in a small quantity of distilled water. The plants were 
then moistened with distilled water by means of an atomizer and 
the spores applied with a camel’s hair brush. Except in a few 
cases where the plants were very large, they were kept under bell 
jars 24-48 hours. If they became dry, they were sprayed again 
the second day. Generally, however, they were quite moist 
when the covers were removed. For part of the work inverted 
test tubes attached to stakes at suitable heights were employed, 
the lower end being lightly closed with cotton wool. The test 
tubes were found to retain the moisture even better than the 
bell jars. Parallel marks were sometimes made on the leaves 
by means of India ink and the spores placed between them. The 
