118 THE AMERICAN NATURALIST. (VoL. XXXIX. 
if there is any anatomical evidence which will determine the 
species with which C. kempferi was crossed; and (3) if this 
evidence bears any relation to the fixity of the form and in any 
way defines a new species. To this end it will be necessary to 
elaborate the separate diagnoses and compare them with one 
another, as also with differences in color, form, and texture as 
applicable to the leaves and flowers. 
Teas Hysrip (Figs. I, 5). 
Transverse.— Growth rings very broad, the spring wood thin but the dis- 
tinction between it and the summer wood not clearly recognizable. The 
wood cells of the earliest growth sometimes tangentially elongated, in more 
or less. obvious radial rows and rather large with rather thin walls ; the struc- 
ture of the later growth chiefly the same throughout the growth ring, the 
cells hexagonal, in somewhat definite radial rows, not thick-walled, very 
variable in size with little or no diminution toward the outer limits. Woo 
parenchyma confined to the composition of the vessels and to the earliest 
spring wood where the cells become distinctly larger and more resinous. 
Wood tracheids prominent, squarish, in very definite radial rows, forming a 
narrow zone of about six elements on the outer face of the growth ring, but 
locally extended radially inward opposite the smaller vessels with which they 
join so as to form tracts of variable width; also uniting with the smaller 
vessels to form a second and more internal, discontinuous zone of very 
irregular width and form. Vessels at first medium and forming a single 
layer with strongly developed thyloses; becoming abruptly larger in the 
second layer, radially oval or oblong and chiefly single, but sometimes 2-3 
compounded radially and tangentially and largely devoid of thyloses ; soon 
diminishing in size and number, radially compounded and much scattered 
in irregular groups of 2-6 throughout the growth ring, finally reduced some- 
what abruptly in the last growth of the season to the dimensions of tra- 
cheids with which they coalesce into irregular tracts. Medullary rays prom- 
inent, numerous, somewhat resinous especially in the spring wood, 1-3 cells 
wide, distant upwards of 178 p. 2 
Radial. — Medullary rays somewhat resinous, the cells straight, rather uni- 
form in height, very variable in length and from 3-4 times longer than high, 
or again very short and much higher ; the upper and lower walls rather thick 
and finely pitted; the terminal walls straight or curved and finely pitted ; 
the lateral walls not pitted except opposite vessels and then with small, 
numerous, oval and unequal pits. Tracheids of the limiting zone with spi- 
ral and scalariform structure which merges into 1—2 rows of simple pits on 
the radial walls. Wood parenchyma somewhat resinous and exceedingly 
variable; when adjacent to the spiral tracheids of the summer wood, very 
