73 
sion of the germ tube. It also provides that eaeli germ tube shall be 
directed at an augle, often a right angle, to the direction taken by that 
of its fellow cell, insuring different' points of infection. In case of the 
entire division of the cells of the conidium, still another aid to imme¬ 
diate dissemination is obtained. In one instance a germ tube was seen 
which originated from a second or inner cell, passed through the septum 
to the terminal cell and out at the end of the latter. (Plate xii, Pig. 23.) 
The germ tubes in moist cultures grow out into long mycelial hyplue, 
which at an early stage appear destitute of septa, but when older the 
septa become distinct and often quite near together. The contents of 
the new hyplue are quite clear and finely granular. The branches are 
not very abundant, but moderately so in some cases. They mostly 
arise at right angles to the parent liypha. The thickness of the parent 
hyplue is well maintained through their length, although diminishing 
slightly to the end. There are, however, some cases where the hyplue 
are enlarged or contracted at various points in their course. Oonidia 
recently matured germinate in moist cultures very readily after a 
period of three or four hours$ those having been matured several 
weeks germinate more irregularly and slowly. 
The mycelium within the host plant is composed of hyplue very simi¬ 
lar to those of germinating spores. At points adjacent to the spore 
clusters the hyplue are apt to make more or less abrupt turns, and at 
the angles they are sometimes considerably swollen. While culture 
hypliae are rarely more than 4 yu in thickness, often considerably less, 
those near forming spore clusters in the leaf may reach 5 jj. in thick¬ 
ness or even more. As the hyplue branch and grow through the tissue 
of the leaf their thickness is reduced till those distant from the spore 
clusters are very fine. In general the hyplue vary in thickness from 3 
to 5 ju. They have been seen in all the tissues of the leaf, and nearly 
always occupy the intercellular spaces. They are seen to wind among 
the cells of the palisade tissue, in some cases going directly down be¬ 
tween those cells to the more loosely arranged palisade tissue or spongy 
parenchyma as the case may be. I have seen numerous hyphse in the 
epidermal cells, and one liypha passed for a considerable distance, from 
cell to cell, through the epidermis. The finer vegetative hyplue are 
quite clear and are not easily distinguished, while their septa are seen 
with much difficulty. The larger hyplue are more distinctly septate 
and the finely granular contents are rather indistinct. The walls are 
distinct under an enlargement of 500 to 800 diameters. 
At or near the center of the affected leaf tissue the mycelial hyplue 
become grouped, either within the epidermal cells or just below them. 
Here is formed a tubercular mass of heavy-walled cells, giving rise to 
erect thick-walled hyplue or conidiophores. The tubercular mass when 
soaked for several days in water may be pressed and teased apart, so 
as to show that it is a compound body made up of groups of thick-walled 
storage cells supported upon a single liypha of the mycelium, These 
