OE BUCKLEYA QUADÏIIALA, B. ET H. 20 



the haustorium provided with the duramen, certain changes occur 

 in the wood in front of the sucker. For instance, here the 

 medullary rays contain very little, if at all, of the reserve starch 

 (Fig. 21). 



These modified tissues of the host extend just so far as the 

 duramen of the haustorium extends. In one instance, I have 

 seen that not only in the part of the host just beneath the 

 haustorium, but even in the part far removed from it, the older 

 rings undergo the same modification into a kind of duramen. It 

 seems therefore probable that the formation of the duramen in 

 the old host-root necessarily induces the same change or process 

 of disorganization in the older tissues of the haustorium, that are 

 connected with the duramen of the host. 



This formation of the duramen in the haustorium was found 

 exclusively in old specimens, which were, judging from the number 

 of the annual rings of the host-root, from fifteen to twenty years 

 old, or thereabout. These old haustoria were discovered by me 

 only on Abies, and the occurence of such a modification in the 

 haustoria found on other hosts still remains undetermined. 



6. The Attaching-Fold, Sucker and Striated Band. 



As has been stated above, the haustorium acquires a few 

 pairs of the folds already during its primary growth ; but after- 

 wards we can observe no increase in their number, and generally, 

 in the old haustorium, they disappear entirely. The question 

 then arises, how do they disappear ? To clear up this question, 

 haustoria of various ages were examined and compared with 

 one another. In the young haustorium the folds adhere, as 



