128 THE AMERICAN NATURALIST. [Vor. XXXIX. 
intermediate position between the first two in such a manner as 
to show the direct influence of the latter in a reduction of both 
size and number in the outer summer wood. This feature is 
again correlated with the distribution of the tracheids. Our 
diagnoses have shown that in C. kempferi these elements form 

Fic. 7,— Catalpa speciosa. ‘Tangential section, X 61. wing the vessels with rather few 
Showi: 
thyloses and the exceedingly high rays of variable width, composed of several rows of 
thick-walled cells. 
a limiting zone which is locally increased in thickness in a radial 
direction opposite the small vessels of the outer summer wood, 
with which they coalesce to form irregular tracts; or again cen- 
tering in small vessels so as to form a second zone of small and 
rather distant tracts. The same feature appears also in C. big- 
nonioides but in such a modified form as to constitute a distinc- 
