8 The Colorado Experiment Station 
the following to be the most tenable and satisfactory soluti of 
the question. 
This phase of the investigation was carried on at Gypsum, 
Colorado, where our first observations were taken May 4, 1909; 
this was early in the spring for this locality and altitude (over 6,000 
feet above sea level). The season was considered cold and back¬ 
ward, and a moderately heavy snow had fallen one week before; 
traces of this were still to be seen in the valleys, and the surround¬ 
ing hills and mountains were heavily covered. 
The alfalfa was just beginning to grow, the average height 
in the diseased fields being from 1^2 to 2 inches. Most of the 
plants had a yellowish green color due, presumably, to the cold. An 
examination of the young, succulent shoots showed that the epider¬ 
mis of practically every one of them was wrinkled just below the 
point of attachment of the first four or five leaves, and often this 
wrinkling extended half way to the next leaf below. The epidermis 
was loose from the tissue beneath and appeared to be too large for 
the stem. When this was peeled off, the underlying tissue had a 
yellowish, green color much like the diseased plants, but a micro¬ 
scopic examination of such material failed to show any micro-or¬ 
ganisms present. In those parts of the stem where this wrinkling 
was absent, the tissue beneath the epidermis was not yellow, but a 
whitish green. In many plants, the loosened epidermis had the 
appearance of partially collapsed blisters, while around and under¬ 
neath these blisters the tissue seemed darker than normal and 
watery, with a suggestion of its having been frozen. Numerous 
lenticular breaks occurred in the epidermis of some stems. These 
might have been due to insect work although rather early in the 
season for this. Occasionally stems were found where the wrinkled 
epidermis had split open for a distance of one centimeter, exposing 
the moist pyrenchyma beneath. 
Ten days later, May 14, the epidermis of practically every stem 
in the field was split wide open from node to node over the first 
six internodes, the third to the fifth internodes being the most 
common. This splitting appeared to have begun with the wrinkled 
epidermis mentioned above, and had extended the whole length of 
the internode thereby exposing the succulent, moist tissue beneath 
to infection. It is the concensus of opinion of those who have ob¬ 
served this phenomenon, that both the breaking away of the epider¬ 
mis from the underlying tissue and the wrinkling and subsequent 
splitting are caused by freezing. A similar trouble ascribed to freez¬ 
ing has been observed in cherry trees and less frequently in the 
apple. Here the bark cracks and later splits open, exposing the 
green wood beneath just as in the alfalfa stems. 
Anyone who has ever lived in Colorado is familiar with the 
