344 The Black Knot. [J ahs, 
germinate in the course of from three to five days, when suffi- 
ciently moist.” - | 
Besides the conidial spores formed from the outside, and the 
ascospores from the inside, of the wall of the perithecia, there 
are still other forms of fruit, which are called stylospores. These 
spores are produced in cavities between the perithecia; a cross 
section of such a cavity is represented in Plate III., Figure 4, 
with a small portion more magnified in Figure 5, showing these 
bodies to be borne on long stalks and divided by partitions into 
four parts. 
“ Plate IV., Figure 2, represents a Section through a cavity 
hardly distinguishable externally from the perithecia, which, in- 
stead of being filled withe asci, is lined with slender filaments 
whose tips are somewhat incurved, and easily broken off, the 
central part of the sac being filled with them. We call these 
“ spermogonia,” from their resemblance to the bodies of the same 
name in lichens, They are much less common than the conidia or 
stylospores. Interspersed amongst the ascus-bearing perithecia, 
one finds tolerably frequently still other cavities which are much 
more flattened than the perithecia, which often, instead of appear- 
ing oval, on section seem almost triangular. They are lined with 
short, delicate filaments which end in a minute oval hyaline body. 
These small oval bodies are produced in immense numbers, and 
are discharged not singly, but in masses. They are more or less 
closely held together by a sort of jelly, and ooze out from the 
cavity in which they are produced in the form of tendrils remind- 
ing one of the toy called “ Pharaoh’s serpent.” This last form 
is called the “ pyenidia.” It seems that this fungus does not 
lack for methods of propagating itself and continuing its species. 
The knot on the choke-cherry, when compared with those on 
the plum and cultivated varieties of cherry, is seen to be slightly 
different in general appearance; but when viewed with the 
microscope they all prove to be identical, the difference notice- 
able to the naked eye being due to more favorable circumstances 
for its growth afforded by one species of Prunus than by another. 
On the plum it does not thrive as well as on the choke-cherry- 
The curculio deposits its eggs in the young pulpy knot, and from 
the punctures a gum soon exudes and on this coating a mold, 
Trichothecium roseum Lk., quickly develops, giving a peculiar 
pinkish color to the knot. “It is probably owing to the fact that 
the curculio stings the knots that so many persons have been led 
to believe that the knots themselves are of insect origin.” 
