390 Cannon : Anatomy of Phoradendron villosum Nutt. 



10. A longitudinal section through the bast of the oak and the tip of a young 

 sinker, the cells of which have for the most part lost their epithelial characters : P, 



parasite ; H, host, X 22 °- 



11. A longitudinal section of the tip of a sinker, radial of the wood cylinder of 

 the oak, which shows the apposition of the pits in the walls of the ducts and in those 

 of the outer cells of the parasite : *S*, sinker ; (9, oak ; D, ducts of oak ; /, pits of host 



and parasite in apposition, X 3 2 °- 



12. A longitudinal section, partly diagrammatic, of sinker, cross section of the 

 oak, showing the effect of the season's changes in pressure of the oak wood cylinder ; 

 S 9 sinker ; C, cortex of oak with the fiber rings indicated by dotted lines ; cam, oak 

 cambium ; Sp, spring ; Sn 9 sumrrfer wood. 



13. A partly diagrammatical sketch of cortical haustorium in oak cortex. The ar- 

 row points to the center of the oak stem : P, parasite ; C, oak cortex ; Sc, sclerenchy- 

 matous cells. 





