394 Cooke and Schively on Observations on the 
cells are not crowded together, but are rather loosened out, 
displaced and altered in aspect. There appear the short 
reticulated and spiral tracheids that characterize the haus- 
torial tissue. Lying among these are the peculiar large, 
dense nucleated cells also found in the haustorial tissue. 
They are extremely large cells. Their nucleus is remark- 
ably large and dense, and contains a small nucleolus. These 
two kinds of cells, the nucleated cells and tracheids, con- 
stitute the haustorial tissue, that shows exactly the same 
structure later, in its extreme ramifications in Epiphegus, 
as it does here. It is a unique tissue, there being nothing to 
resemble it in any structure of Epiphegus. In Epiphegus, 
the cells all show a definite arrangement. The tracheids lie 
alongside each other in long rows, and thus form continuous 
tubes. The nucleated cells also lie in regular rows. Prob- 
ably the function of the tracheids is to pass over the flow of 
sap from the beech-root into the parasite. The appearance 
of the nucleated cells is certainly that of very actively meta- 
bolic cells. Quite probably they function in chemically 
transforming this beech sap so as to be used in the tissues of 
the parasite. 
This peculiar tissue can be seen passing from the beech- 
root directly over into the parasite. At the point of cross- 
ing, a strong constriction is evident, the cells being greatly 
stretched out. The epidermis of the parasite and host is 
completely continuous along both sides of the connection. 
Immediately on entering, the haustorium divides, and sends 
two columns in exactly opposite directions. In tubers where 
the haustorium enters from below, these two arms go right 
and left in a horizontal direction. In the one being de- 
scribed, when the entrance was on the side, the two arms 
go above and below in a nearly vertical plane. The down- 
going column soon divides again, sending out two arms that 
diverge right and left in a nearly horizontal plane. After 
this there stream off various fine endings of the haustorium 
in various directions. 
