1916] 
GILMAN—CABBAGE YELLOWS 45 
Hosr RELATIONS 
MORPHOLOGY 
The distribution of the fungus in the living host tissues is 
limited to the vascular bundles. This fact was first shown 
in making plates from old stems of diseased plants. The stems 
were cut cross-wise in thin sections and, after sterilization 
in hydrogen peroxide for five minutes and washing in sterile 
water, were laid on the surface of poured plates of potato 
hard agar. Invariably the first growth of the mycelium ap- 
peared from the fibro-vascular ring (pl. 2, fig. 14). Upon dis- 
section of diseased seedlings the hyphae were demonstrable 
` 
Fig Cross-section of vascular bundle from diseased 
cabbage stem, showing distribution of fungus in vessels. 
Note preponderance of cut ends of hyphae. Stained with 
Pianeze IIIb. Camera lucida sketch x 1000. 
traversing the lumina of the bundles longitudinally. The stems 
were first boiled for five minutes in a 5 per cent potassium 
hydroxide solution and then dissected under a hand lens. 
The final examination was made under the compound micro- 
scope. In no case was a very large amount of mycelium 
found in any single vessel (fig. 7). 
In later work the diseased stems were imbedded in paraffin 
in the usual manner, after fixing in Gilson’s solution, and 
stained with Pianeze IIIb, as recommended by Vaughan (214). 
The fungus stained а deep red, while Ше host tissue was col- 
