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tion. The very large mass of corroborating positive evidence, though 
really conclusive only when based on single-organism cultures, makes it 
extremely probable, to say the least, that such saltations or mutations 
do occur in these groups. 
Among the Eumycetes several examples occur of what appears to 
be saltation. Edgerton (50) in 1908, writing of Glomerella rufomaculans, 
states that ‘‘of the more than thirty collections studied from over twenty 
hosts, with less than a half-dozen exceptions all gave at least slightly 
different characters. Even the two collections on apples from Missouri 
and Illinois did not give exactly the same characters, but the differences 
were slight. The two collections from apples in the north, however, gave 
entirely distinct characters from the more southern forms on the same 
host. The southern form, especially on sugar medium, was characterized 
by very rapid growth and a very dark greenish-black color of the sub- 
stratum and aerial hyphae; while the northern form grew more slowly 
and had very little dark color. Generally in the latter the aerial hyphae 
were colored pink from the profuse development of conidia. Even the 
form on quince collected in New York did not give the same characters 
as the northern form on apple. The forms on orchid, Coffea, and Sar- 
racenia, collected in the same greenhouse at the same time, were not 
exactly alike in culture media.” 
Other examples were given by Edgerton (50) in 1908 of what appears 
to be the same phenomenon as that under discussion here, but as there 
is no evidence that he worked with single-conidia cultures* his apparent 
variations may have been due—though it is highly improbable—to segre- 
gation of elementary species. His general conclusion follows: ‘“The only 
explanation of the phenomenon is that one or more individuals of the 
original form changed quite suddenly their course of development under 
cultural conditions. It is undoubtedly a Gloeosporium of the Glomerella 
type, with the development of the perithecia considerably different from 
other known forms. Mutations, so far as is known by the writer, have 
not previously been recorded among fungi, but the form just described 
seems to be one without question.”’ 
Here, too, should be mentioned the plus and minus strains of Glom- 
erella studied and reported on by Edgerton (51) from single-conidia cul- 
tures, though this may represent a differentiation of sexes rather than of 
races. He gives several citations which indicate that other workers have 
*In a personal letter dated February 7, 1921, he writes regarding this as follows: ‘“‘All of the cultures 
that I used in that work were obtained by the dilution plate method and presumably came from single spores.” 
