-~ 
—- ‘ 
; LITERATURE ON BUNT O} WHEAT. 7 
of bunt upon the stem “in which the fetid smell and peculiar structure 
were not to be mistaken.” Evidently he was ignorant of Prévost’s 
' work, for he says (14) that he believes himself to have been the first to 
| observe the fusiform sporidia, although he misinterpreted them. In 
1857 (45) he correctly figures the germination and development as 
far as the formation of secondary sporidia. 
_ The controversy between those who recognized fungi as causes of 
_ plant diseases and those who regarded them merely as symptoms or 
effects of plant disorders raged from 1800 to 1860, and the briefest 
_ review of the writings of this period would extend this bulletin beyond 
reasonable limits. Of those who, by their investigations and writings, 
3 have contributed to the establishment of the parasitism theory, the 
i ollowing deserve special notice: De Candolle (74, 75, p. 1435-1438), 
Banks (8/), Prévost (312), Rudolphi (33/), Tulasne (377), Léveillé 
- (289), Berkeley (43, 44), and De Bary (34, 35). The leaders of the 
| opposition were Unger (379, 380, 381), Meven (268), and Fries (126). 
In so far as bunt and other covered smuts were concerned, the con- 
_ troversy ended with the work of Kitihn (220, 223), and Wolff (398), 
who demonstrated the entrance of the mycelium at the root node or 
_ between it and the point of the leaf sheath. The work of Maddox 
_ (255, 256), Hecke (144), and Brefeld (61, 62) in proving the blossom 
infection of the loose smuts put them in a class apart from the bunt 
and covered smuts and facilitated in great measure the further study 
hae 
of both classes. 
we 
THE KUBN OR MODERN PERIOD. 
Kuhn (220) observed what he conceived to be the entrance of the 
_ fungus threads into the host plant through the leaf sheath and stated 
_ that it grew across, through the leaf layers, to the growing point. 
___ The next successful experiments were those conducted by Wolff 
(398). He investigated several smuts, but principally the stem smut 
of rye, Urocystis occulta (Wailr.) Rabenh. His conclusions were that 
Poy oe ROS 
ail ily 
J 
_ the rye-smut organism entered the host, not necessarily at the root 
: node, but within 8 or 10 millimeters aboveit. Wolff observed that the 
_ mycelium, while passing through the epidermal cell, was inclosed in a 
ulose sheath, and that after this passage its growth within the host 
_ became intercellular, pushing haustoria into the cells. With the smuts 
_ of wheat, oats, and barley. Wolff claimed that the mycelium was, in 
_ general, intracellular. In 1874 Kiihn (223) announced that infec- 
_ tion could take place at almost any point in the seedling. 
_ After Kiihn, Brefeld carried on an extensive series of inoculation 
_ experiments, using sporidia produced in pure culture (see Ward, 
390). He maintained that the fungus could enter the plant at any 
_ point where it could be brought in contact with meristematic tissue. 
He asserts also that he found the mycelium in all parts of the young 
_ growing plant, from the root hairs and roots upward, and that he 
_ obtained infection by passing the inoculum downward to the growing 
. posit through the rolled leaves by means of a capillary tube. In this 
atter case he says that many points of entrance could be discovered 
when the material was killed soon after the inoculation, but that the 
openings soon closed and became invisible with the growth of the 
plant. Brefeld used oats and barley and their smuts in his inocula- 
_ tion experiments, so his results may not be entirely applicable to 
 Tilletia. 
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