OF BUCKLEYA QUADRTALA, B. ET H. 39 



in thickness is accomplished. The cambium of the haustorium 



joins that of both the host and the mother-root, and together 

 forms a complete thickning ring. Any noticeable secondary growth 

 in length does not take place. 



2. The form and structure of the haustorium are changeable 

 according to age. 



3. In earlier stages the axial part of the haustorium has 

 an elliptical form in cross-section, which has its major axis 

 coincident with the longer axis of the host-root, but after a certain 

 stage, owing to the more vigorous growth in lateral direction it 

 becomes circular and then again takes an oval shape, with its 

 major axis in the place of the minor axis of the former ellipse. 



4. The haustorium possesses medullary rays. 



5. The existence of sieve-tubes cannot be definitely ascer- 

 tained. 



6. The striated band in the cortex disappears in the older 

 haustorium. 



7. The attaching-folds undergo the same fate. At first, they 

 detach from the host-root, project at the margin of the apex of 

 the haustorium and sometimes produce striations or furrows. 



8. The sucker, easily distinguishable in the younger stage, 

 loses its demarkation from the part behind it after a certain 

 degree of growth. 



9. So long as the host-root is alive, the haustorium may 

 be active and can maintain its life during many years. 



10. Demarkations between the zones produced in each period 

 of growth are visible, though faintly, in the vascular strand of 

 the haustorium. 



11. In the older haustorium the older part of its axis goes 

 into the formation of the duramen. 



