28 BULLETIN 759, U. S. DEPARTMENT OF AGRICULTURE. 
which might have prevented infection even had the spores been 
present. 
At this point, it is convenient to mention an English disenssiion. of 
this disease by Ivy Massee (1914) in-which an effort is made to 
throw light on the method by which the fungus is conveyed from one 
locality to another. In this article Miss Massee states that so far as 
England is concerned the dissemination of the disease is due to 
diseased seed which is badly cleaned. She says, “I have recently 
examined a sample of commercial seed and found the fungus present 
in abundance on minute fragments of leaves and calyces, and rarely 
on the seed itself.” Unfortunately, Miss Massee does not state the 
methods by which she was able to make the identification of the 
fungus with such certainty on this single sample of commercial seed. 
Even if she was correct in this observation, it still remains to be 
proved that the fungus which she found was alive and capable of 
infecting the plants grown from this seed. 
The many scattered observations of the disease merely contribute 
data regarding distribution, seasonal occurrence, and environmental 
factors. Most of these reports indicate that the disease is worse on 
plants during the first summer of their growth than later, but 
Coombs (1897) speaks of attacks as being worse after the first year. 
Most reports indicate that the disease usually gains headway slowly 
in the spring and becomes worse later in the season, but this is not 
always the case. Stewart, French, and Wilson (1908, p. 384-387) 
speak of the disease as being worse in dry years while most reports, 
especially from drier regions, indicate that the disease is worse in 
wet seasons. 
The facts bearing upon the overwintering of the fungus in the 
field are surprisingly meager. The only definite bit of observational 
evidence is that of Chester (1891), who states that he found live 
asci on leaves in midwinter. Voges (1909) suggests in addition that 
the fungus survives the winter in living leaves. 
After surveying these scattered references in American. literature 
we find that there is a general belief that Pseudopeziza medicaginis 
is distributed with the seed and survives the winter on dead leaves. 
This opinion has been reached, not so much as the result of careful 
experimental evidence, which in fact is meager, but more as the 
cumulative effect of the expressed opinions of competent observers 
who have watched its development during a series of years. 
METHOD OF OVERWINTERING. 
The first evidence of the method of overwintering of the leaf-spot 
fungus in the field was obtained in the spring of 1916. On April 11 
overwintered alfalfa leaves showing abundant Pseudopeziza spotting 
were brought into the laboratory and placed in a moist chamber. 
