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worked, differed in a very fundamental way, as pathogenes, from those 
which I am studying, his forms being intracellular (except as regards 
the first cell invaded), and not at once killing the adjacent cells. That 
is, the condition pictured is much like that presented by Albugo, Perono- 
spora, Puccinia, etc., except for the absence of haustoria. The forms 
with which I deal, on the other hand, though they enter through the middle 
lamellae, immediately become intracellular and at once kill the protoplast 
of the invaded cell, and proceed similarly with other cells. These differing- 
conditions, if substantiated by further study, probably indicate funda- 
mental differences in the fungi in regard to their production of toxins or 
enzymes, and certainly indicate an entirely different type of pathogenicity. 
In these early stages the disease is properly a spot and not a rot. Whether 
it will develop into a true, general rot depends upon conditions. Phenomena 
like those described under the present heading, though differing in de- 
tail, were noted with H. Nos. 6, 8, 9, 14, 21, 36, 39, 40, and 41. 
Action of various strains of Helminthosporium on wheat shoots —Tests 
in rag doll, at medium moisture, with H. No. 1 and H. No. 3 gave at 2 
days 100% infection for both; at 6 days there was no appreciable difference 
between the two; while at 10 days all shoots were rotten under H. No. 1 
and some, but not so many, under H. No. 3. The test was repeated with 
14 strains of Helminthosporium. All strains at 2 days showed 100% 
infection; the controls, no infection. The infection phenomena with all of 
these strains were all of the character described on pages 128, 129, showing 
penetrating mycelium, “‘callus,’’ etc. At 6 days H. Nos. 1, 4, 5, 8, 13-16, 20, 
and 21 had all produced some rot. The roots also were distinctly yel- 
lowed by H. Nos. 15 and 16, while H. No. 20 showed less rotting than 
the other numbers mentioned above. H. Nos. 29 and 39 produced no 
rotting, and the lesions were visible only through a lens, but thus viewed, 
showed 100% infection, as indicated by the usual infection phenomena. 
H. Nos. 3, 6, 9, 17, and 18 remained local, as at 2 days. H. No. 29, a 
Helminthosporium with geniculate conidia, germinated abundantly from 
both ends of the conidium, and on wheat produced many penetrating 
mycelia and an abundant mycelium within the host, though the mycelial 
invasion reached only a few cells, and while extending for a considerable 
distance lengthwise, made but little progress laterally. The appressoria 
were usually pyriform, as was also the penetrating mycelium, differing 
thus from H. No. 1 (Fig. 17). Similar tests were made with three saltants, 
M6, M8, and M38. Notes at 2 days showed 100% infection, and at 6 
days much rot by M6, and considerable rot by the other two. 
