May a6,1923 
Gramintcolous Species of Helminthosporium 
701 
probable identity of the parasite to H, sativum. It is interesting to note, 
however, that in the vicinity of New York City and Washington, D. C., 
during the seasons of 1920 and 1921, meadow fescue was not observed 
affected with the spot blotch described from Iowa, although very com¬ 
monly showing the symptoms of the net blotch disease discussed else¬ 
where in this paper. 
In addition to the graminaceous species already discussed, the literature 
contains references to successful infection of other species, by artificial 
inoculation with strains of Helminthosporium that, as has been pointed 
out, may be referred to H. sativum. Thus Massee (90) secured growth 
and abundant sporulation by transferring spores of the fungus he regarded 
as H. gramineum to leaves of Festuca ovina, Briza media, Dactylis glomerata, 
Poa annua, and Arrhenatherum avenaceum that had been cut off and 
incubated in a damp chamber. Stevens {141) secured infection of Sudan 
grass and millet as a result of inoculation with the footrot organism. 
E. C. Johnson (71) found that the strain of Helminthosporium isolated 
by him from the node of a wheat plant seriously attacked the foliage 
of young oat seedlings. L. J. Stakman (13S) reports positive results 
from the inoculation of over a dozen new hosts with strains originally 
isolated from wheat and from rye. Taken altogether the results are 
not in complete harmony, a fact which may probably in part be explained 
by differences in the conditions under which the experiments were car¬ 
ried on. The method employed by Massee certainly would seem to 
make for an inordinately extensive experimental host range. On the 
other hand, the existence of biological races, corresponding to those of 
stem rust (Puccinia graniinis) for example, is not outside the realm of 
possibility. Indeed, absolute agreement in regard to host interrelations 
between different strains of a fungus attacking so many alHed gramina¬ 
ceous species as H. sativum could, perhaps, scarcely be expected. 
MORPHOIvOGY OF THE FUNGUS 
The fructifications of Helminthosporium sativum make their appear¬ 
ance after the death of the affected tissue, emerging from the stomata 
or more frequently between the epidermal cells singly or in fascicles of 
2 or 3. (PI. 17, Ea-e.) According to Pammel, King, and Bakke (104), 
the sporophores vary from 8 to 10 /z in width, but these figures appear 
somewhat too high, the measurements for this dimension varying 
usually from 6 to 7 ju, and rarely exceeding 8 ju. The first spore is 
produced generally at a distance of 50 to 90 /x from the base. The scars 
marking the points of attachment of successive spores at well-defined 
geniculations occur at very variable intervals, approaching 5 /x as a 
minimum limit, and occasionally exceeding 60 ju. As found in nature, 
the sporophores rarely show more than 5 or 6 scars or more than 8 
septa, the distances between the latter usually varying from 5 to 40 /x. 
The measurements for H. teres given by Bakke {6), 150 to 180 jit by 60 
to 80 IX, while obviously incorrect for the width of the sporophores of 
the causal organism of spotblotch or “late blight'^ of barley, probably 
as a result of a typographical error, are also sufficiently in excess of the 
usual range in length of these structures, no to 150 /x, to indicate that 
this author was, indeed, in this instance referring to the parasite causing 
netblotch. 
Such indication is strengthened by the portions of his description of 
the spores referring to their length and color, “ 150 to 130 /x,” and “pale 
