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PERENNIAL MYCELIUM OF THE FUNGUS OF BLACKBERRY RUST.* 
Plates V, VI. • 
By F. C. Newcombe. 
In May of the present year, at the suggestion of Mr. Galloway, a plant 
of Rubus villosus affected with Cceoma nitens , Schw. was examined with 
a view to ascertaining whether there is a perennial mycelium. 
A shoot of the blackberry was selected whose lowest leaf bearing the 
rust was 10 centimeters from the rooting portion of the stem. Begin¬ 
ning with the leaf, cross and longitudinal sections were made, at inter¬ 
vals of 2 centimeters, down to the roots. 
At every place of section the characteristic mycelium was found. In 
one instance the mycelium was observed in the medullary rays; in 
every other case in the pith only. It is septate, intercellular, and 
coarsely granular. It looks active and vigorous in the old stem as well 
as in the green shoot. But the most striking part of it is the haustoria. 
These are found of the same appearance in leaf, green shoot, and old 
stem. Penetrating the cell wall by a narrow neck, in the cell-lumen a 
haustorium expands to a large, iobed and knotted, club-shaped body 
whose diameter exceeds that of the mycelial filament and whose length 
frequently attains the transverse diameter of the host cell. In longi¬ 
tudinal sections the mycelium can be followed for long distances in the 
direction of the shoot axis, not often branching laterally, but sending 
its great haustoria in all directions into the adjacent cells of the host. 
Not infrequently the mycelium is seen to form a pseudoparenchyma in 
the intercellular spaces. 
These observations were repeated on fresh material gathered near 
Ann Arbor the latter part of June. 
NOTE BY B. T. GALLOWAY. 
Mr. Newcombe’s observations have an important bearing on the treat 
ment of blackberry rust, as they indicate that no direct benefit would 
result from the application of fungicides. Some writerst have claimed 
that the fungus does not live over winter in the root and stems, and if 
this were true it would seem possible to prevent the disease by the 
timely application of fungicides. Field experiments have shown that 
such applications, no matter how carefully made, have little effect so 
far as diminishing the amount of rust is concerned. 
It is obvious that the immense number of spores, which form the red 
dish powder so familiar to every one, plays an important part in the 
life history of the fungus, and by destroying these spores, spraying may, 
indirectly, result beneficially. It is doubtful, however, if spraying with 
this object only in view will pay in the end. After all, it seems that 
* Cworn a nil (ns, Sclnv. 
t Burri 1, Prairie Farmer. 1885, p. 762. Seymour, Kept. Stare Hort. Soo Minn 
188H, p. 214. 
