126 THE AMERICAN NATURALIST:  [Vor. XXXIX. 
5 cells wide. These features are of so pronounced a nature as 
to leave no doubt whatever as to the fact that C. speciosa is not 
in any way concerned in the production of the hybrid, since none 
of its characteristics are to be met with in the latter. It now 
becomes necessary to determine as a final factor, whether the 
features of the hybrid which we have already seen cannot be 
accounted for as being derived from C. kempferi, are in any 
way attributable to C. bignonioides. 
C. bignonioides (Figs. 4, 8). 
Transverse— Growth rings very broad. The summer wood not sharply 
defined but distinguishable by (1) the smaller size of the wood cells, (2) the 
reduction of the vessels, and (3) the presence of groups or tracts of tra- 
cheids. Spring wood composed of large, variable, hexagonal, and tangen- 
tially elongated cells in somewhat obvious radial rows, the walls thin; soon 
replaced by the smaller and radially extended cells of the summer wood 
which diminish very gradually toward the outer limits of the growth ring. 
Wood parenchyma confined to the structure of the vessels. Tracheids 
rather thick-walled, non-resinous, squarish or tangentially extended, in 
radial rows confined to the outer portions of the growth ring where they 
form irregular and tangentially extended tracts of variable, often great 
extent in two series; the inner rather broad and strictly tangential, the 
rather large tracts more or less confluent and continuous, the outer formed 
of narrow, diagonal and chiefly free tracts projected inwardly from the 
outer limits of the growth ring. Vessels of the spring wood with strongly 
developed thyloses, at first large, oval or round, single and strongly pre- 
dominant; soon becoming 2-3 compounded in radial series and steadily 
diminishing in size, shortly becoming single and more distant, and finally 
replaced wholly by groups of tracheids. Medullary rays prominent, 1— 
several cells wide, sparingly resinous, distant upwards of 462 
Radial. — Medullary rays sparingly resinous; in the spring wood the cells 
are upwards of six times longer than high, the upper and lower walls very 
thin and barely pitted, the terminal walls thin and finely pitted, the lateral 
walls with occasional fine and simple pits; in the summer wood the cells 
are often not much longer than high, the upper and lower walls finally 
rather thick and strongly pitted, the terminal walls rather thick and finely 
pitted, the lateral walls when opposite vessels with rather small and com- 
monly numerous, oval, simple pits in more or less definite radial series. 
ood parenchyma of the first spring wood composed of short-cylindrical 
and rather broad cells, the radial walls with numerous, transversely oval 
or oblong, simple pits. The tracheids of the summer wood narrowly cylin- 
drical and showing all transitional forms from spiral and scalariform to 
