562 
Notes. 
lately published are not convincing, and that a tendency exists to 
draw conclusions from imperfect evidence. 
I shall show that the way into the tuber is prepared for bacteria by 
fungus-hyphae, and the open passages of destroyed vascular bundles 
afford them ample space. The disease I have studied has appeared 
in a more or less epidemic form at least twice in my experience : it 
was very common two years ago, and this year has been abundant in 
various parts of England. In a subsequent publication I shall show 
that it is common and widespread, and even known in some countries, 
though not adequately recognized. 
Symptoms. — The shoots turn yellow and die prematurely during the 
summer, and before the tubers are anything like full. The disease 
starts from below and not from the leaves. The roots are few and 
poor, and soon rot away. The tubers are few, do not mature, and 
often rot in the ground. The leaves turn yellow and wither on the 
stems, with the symptoms of premature wilting , and often remain long 
hanging on the yellowing, glassy-looking, but still living stems. 
In very mild cases these symptoms are not obvious, and supervene 
slowly, and the case may be complicated by the coexistence of 
Phytophthora. In very severe cases, on the other hand, especially in 
wet situations, the stems and roots may be all rotten by the end of 
July, and casual observation may ascribe the damage to Phytophthora 
entirely. In ordinary cases, again, it is easy to suppose the damage 
due to some insect attack, or to drought. 
In advanced stages of the disease the stems either dry up to brown 
sticks, or putrefy on the wet ground ; very often bacteria have gained 
access to the tissues at a comparatively early stage. 
Microscopic Appearances. — Sections across the lower parts of the 
attacked stems show one, two, or more of the vascular bundles yellowish- 
brown — visible even without a lens — and the principal vessels of these 
contain branched, septate hyphae. In several cases I have traced 
these hyphae through every internode of the stem, into the petioles of 
the still hanging leaves, into the young lateral shoots, throughout the 
roots and subterranean rhizomes, and up to and even just into the tubers. 
In two cases I have done this in one and the same potato-plant, and 
so have no longer any hesitation in ascribing the disease to this fungus, 
the morphological features of which will be described in a subsequent 
paper. In advanced cases the brown vessels are stopped with a 
yellowish gum-like substance. Tyloses are common in the vessels of 
