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 Epiphcgus, 

 as it does here. It is a unique tissue, there being nothing to 

 resemble it in any structure of Epiphegus. In Epiphcgus, 

 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. 



