No. 459.] ANATOMY OF CATALPA HYBRIDS. 135 
long, their upper, lower, and terminal walls rather thick and obviously pitted, 
their side walls pitted opposite vessels. Tracheids of the limiting zone 
spiral and scalariform and exhibiting transitions to bordered pits. ood 
parenchyma cells variable but narrowly cylindrical, the radial walls with 
numerous transversely oval, simple pits. The radial walls of the vessels 
with numerous, multiseriate, hexagonal pits. 
Tangential.— Rays usually numerous and multiseriate, the cells small 
and thick-walled. 
Synopsis of Species. 
Resinous wood parenchyma in concentric zones one cell thick. 
Vessels of the primary zone large, oval, devoid of thyloses; those of 
the secondary zone small, very numerous, much compounded. 
Rays (tang’l) numerous, low to very high, unequally multiseriate, 
upwards of 5 cells wide. : 
Ray cells (tang’l) small, round or oval, thick-walled, variable. 
I. C. speciosa. 
Wood parenchyma sparingly resinous, the cells scattering and chiefly con- 
fined to the composition of the vessels. 
Vessels chiefly large, not much compounded, scattering and gradually 
diminishing toward the outer face of the growth ring. 
Rays (tang’l) numerous, medium, 1-3 cells wide. 
Wood tracheids in two zones ; the outer composed of chiefly 
free, radially diagonal tracts; the inner of rather broad, 
variable and tangentially extended contiguous tracts form- 
ing an almost continuous zone. 
‚ Vessels of the primary zone large, oval or round, with 
few thyloses. à 
Ray cells (tang’l) thin-walled, hexagonal. 
2. C. bignonioides. 
Rays (tang’l) numerous, low to medium, 1-3 cells wide. 
Wood tracheids in one zone, forming a continuous limiting 
layer with radial extensions opposite small vessels with 
which they unite, sometimes giving rise to detached groups 
which thus form a second, discontinuous zone. 
Vessels of the primary zone small to medium, round, 
with strongly developed thyloses, abruptly enlarging 
in the secondary zone and finally becoming 2-3 com- 
pounded radially. 
Ray cells (tang’l) rather thick-walled, hexagonal. 
3. C. kampferi. 
Wood tracheids in two well defined zones ; those of the outer 
forming a continuous and rather uniform limiting layer 
upwards of 8 elements thick ; those of the inner zone form- 
