No. 459] ANATOMY OF CATALPA HYBRIDS. 125 
A careful analysis of this diagnosis shows that the most 
marked deviations from the characters embodied in the hybrid, 
are to be found in (1) the growth rings which are always several 
times less in radial extent and far more porous, (2) in the charac- 
ter of the initial layer of vessels which are always very large and 
devoid of thyloses, (3) in the character of the vessels of later 

Fic. 6.— Catalpa kempfert. Tangential section, X 61. oct. vessels with numerous thy- 
loses and the low, rather numer ys of lenticul wards of three cells wide. 

growth, which are always much compounded and much smaller, 
their reduction from those of the initial layer being abrupt, (4) 
in the presence of numerous resinous wood parenchyma cells 
which lie in definite, concentric zones of one cell in width, (5) 
in the tangential aspect of the medullary rays which are exceed- 
ingly variable in height, of very unequal width and upwards of 
