A Stem Bught of Field and Garden Peas 
9 
many of the surrounding cells of the underlying parenchyma to be 
filled likewise. (Fig. I.) The infection appears not to extend into 
the medullar parenchyma, stereome, or vascular bundles. Neither 
in the field nor when artifically inoculated in the greenhouse, have 
we observed the vines, as a whole, to wilt; however it is not un¬ 
common to see the petioles and leaflets in this condition. 
Frequently plants that have been inoculated artificially show a 
gradual wilting, or perhaps better designated as withering, in two 
or three weeks after infection, but not the sudden and complete 
KIG. I 
prostration of the entire structure such as is usually meant by the 
term wilting in the technical sense. Owing to the lack of satis¬ 
factory histological material, we are unable to say in the latter 
case whether or not there has been an actual invasion of the vascular 
system. 
ISOLATION OF THE CAUSAL ORGANISM 
The material from which the first isolations were made was 
collected at Antonito, Colorado', June 4 , 1915 . None of the tissue 
was given any preliminary sterilization previous to plating, but care 
was exercised not to use any that was clearly and unquestionably 
contaminated by soil or otherwise. Dilution plates were made June 
5 th in -f 10 nutrient agar, three plates being used in each case. 
These were incubated for 60 hours at 28 ° C., at the end of which 
time colonies were plainly visible. 
Original Isolations from Field Material, June 5 , 1915 
No. I. Stem .—A recent infection; tissue bright and fresh 
appearing, but watery and discolored well up on the stem; thin 
transverse section used for plating taken from' near growing tip 
where disease was just developing. Colonies appeared in 60 hours; 
grayish white by reflected light, bluish cast by transmitted light. 
