DopGE AND ADAMS: PERIDERMIUM CEREBRUM 259 
has been noted by Arthur and Kern* and others. We find 
that the spermogonia are not definitely 
delimited units. The spermatia are de- 
veloped from an extensive palisade layer 
of spermatiophores spreading out in- 
definitely over the surface of the gall, 
thus producing a typical caeoma-like 
structure. Our conception of the mean- 
ing of the terms spermogonium and 
pycnium must be broadened if we are to 
use either of them in describing this 
structure. 
In the New Jersey material it has 
not been possible to determine with ac- 
curacy very long in advance those swell- 
ings which will develop aecidia. The 
tissue in which aecidia are developed is 
usually sloughed off by the following 
spring. It appearsas a dry corky layer, 
the surface of which possesses the cere- 
broid outline, due to the aecidial scars. 
The aecidium primordium has been ob- 
served in cross sections of material as 
early as April 29. At this time it ap- 
pears as an extensive, deep-seated yel- 
lowish layer in the cortex, where it can 
be easily recognized. The cells of the 
cortex in the region of the primordium 
are conspicuously separated by the 
abundant development of the vegeta- 
tive mycelium. Тһе outer two or three 
rows of cortical parenchyma cells are 
pushed outward by the primordium. 
The relation of the primordium to the 
host tissue may best be understood by 
referring to TEXT-FIGURE 3. This figure 
is drawn from a section of the cortex in 
IG. 3. Section through 
aecidium primordium from ma- 
terial collected at Bedford, Vir- 
ginia. s, sclerenchyma; c, cork; 
parenchyma; г 
hyphae; f, fusion cells; b, basal 
tissue. 
* Arthur, J. C., & Kern, F. D. North American species of Peridermium on pine. 
Mycologia 6: 109—138. 1014. 
