ConopJioHs amcncaiia. 1 1 



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. i. 



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 which 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 



