Conopholis americana. II 
chyma, covered with bark and held together by soft delicate 
tissue. 
It was very difficult to get vertical sections of any of these 
tubercles, owing to the large quantity of sclerenchyma, the 
softness of the connecting tissue, coupled with the very differ- 
ent character of the oak root. Still the photomicrograph 
reproduced in Plate V, Fig. 5, gives a very fair idea of the 
state of affairs, although it is not quite through the middle of 
the tubercle, and does not, in consequence, show at its apex 
the scale leaves which cover over and form a part of the very 
young flower bud, which was noticed in Plate VI, Fig. 1. 
The ‘“‘bark”’ is very thick and clearly made up of several 
layers. Below it are patches of sclerenchyma that lie em- 
bedded in soft, rather long-celled tissue, which, both in the 
photograph and in reality, takes the form of anastomosing 
lines. Completely surrounding the patches of sclerenchyma, 
at the base of the flower stalk and in it, this becomes gradually 
transformed into vascular and parenchymatous tissue. 
The apparent line of demarcation between this tissue and 
that of the oak host is plainly shown in the photograph. It 
extends longitudinally across, with downward invasions, into 
the solid oak below, which, in its turn, spreads out fan-wise 
above. 
At first sight it would seem that this strongly marked line 
was the separation between parasite and host; that all above it 
was certainly C. americana, and all below was equally cer- 
tainly Quercus rubra. There are, however, one or two objec- 
tions to this: 
The sclerenchyma patches strikingly resemble such as the 
oak normally develops, in a more limited quantity and at a 
later period, in the cortex tissue. At the same time the rami- 
fying soft tissue is plainly and unmistakably that whick after- 
ward becomes differentiated into the fundamental and the 
vascular tissue of the parasite, so that above this line of appar- 
ent separation there is a possibility that both host and parasite 
