170 
usual. They are apt to be shorter and thicker on the apple, and in 
dry than in moist surroundings. 
Mycelium .—The mycelium is septate and branching, usually color¬ 
less, but may become darker colored with age. It is both intra and 
inter cellular, preferably the latter. In the apple it is sometimes so 
thick just below the epidermis that it nearly forms a continuous sheet, 
the threads lying parallel side by side. 
The spores begin to germinate in water in about six hours. They 
swell considerably. The vacuole disappears, but the spore contents 
pass into the germ tube and the spore is either left partially empty or 
filled with very thin, slightly refriugent protoplasm. 
In several germination experiments secondary spores were produced 
in large numbers. What the conditions were that decided their ap¬ 
pearance could not be determined. They were produced both in nutri¬ 
tive media and water, but seemed to be especially numerous where the 
ends of the hyplne came in contact with some hard substance like the 
cover glass, and in two cases the addition of an extra drop of nutritive 
medium had the elfect of stopping their formation. They may be formed 
on the end of the germ tube when it is no longer than the spore itself, 
and as the mycelium becomes better developed nearly every branch 
may produce a secondary spore on its end. They are developed as 
simple, colorless expansions of the end of the tube, which soon becomes 
delimited from the rest of the hypha by a septum. The walls become 
thickened and dark colored, the contents nearly transparent, and 
a bright spot, strongly refracting, like an oil globule, makes its ap¬ 
pearance in the center. The mature spore has a very faint olive tinge 
and is nearly ovate in outline, being truncate at the smaller end on 
account of the septum which cuts it off from the hypha. They only 
retain their original regular form for a short time, the walls soon push¬ 
ing out in all directions, thus forming a very irregularly lobed body. 
Sometimes these secondary spores send out a germ tube, and when this 
happens the bright spot disappears and the spore becomes lighter col¬ 
ored, the contents having apparently been exhausted. More often, 
however, the mycelium branches just below the point of insertion of the 
secondary spore, and even in this case the latter sometimes undergoes 
the changes just described. 
The contents of the growing mycelium are at first granular, later 
becoming more homogenous, and by the time they have reached the 
stage illustrated in Fig. 7 b occasional vacuoles make their appearance. 
Septa are formed soon after germination. 
Setce .—In a few cases brown seta) have been found in the pustules, 
both on the apple and on the grape, but mostly on the latter. They do 
not seem to be sufficiently constant or numerous to characterize the 
species. Where found they are two or more in a pustule, are septate, 
and of varying length. 
Except for the shape and color of the spores this fungus would seem 
from the description to be identical with that of bitter rot of grapes 
