No. 459.] ANATOMY OF CATALPA HYBRIDS. IIS 
importance of this latter point of view was the more strongly 
impressed upon me because, in the course of studies relating to 
the recognition of species among the North American Coniferales 
as determined by the anatomy of the woody axis, I had been 
obliged to adopt the working hypothesis that there are no varie- 
tal forms in the sense commonly employed and as expressed in 
variations of the external organs, and that where these variations 
arise, they define species as certainly, though not as conspicu- 
ously as in other cases. Fortunately I already had in my posses- 
sion, wood of C. bignonioides and C. speciosa, while fresh material 
of the latter was also obtained from trees growing in the grounds 
of McGill University. About twenty years ago, a specimen of 
Teas hybrid was planted out in the College grounds, and it has 
proved perfectly hardy up to the present time, though two other 
specimens planted about eight years ago were completely killed 
during the two winters of 1902 and 1903. ` Recently Mr. Burton 
Landreth of Bristol, Pa., who possesses a growth of C. kempferi, 
very kindly sent me a specimen of wood, and it has thus become 
possible to bring the wood structure of the hybrid into direct 
comparison with that of the three species among which its par- 
ents are to be found. Later specimens of C. kempferi from 
Mr. J. G. Jack of the Arnold Arboretum, have also enabled me 
to institute more extended comparisons. Before proceeding to a 
discussion of the results obtained, it will be desirable to recall 
the essential features of the hybrid as given by Sargent, and 
to see the direction in which such evidence tends. 
«'The hybrid is an erect, vigorous and rapid growing tree, 
with the thin, scaly bark of the American species. The leaves 
of this tree are much larger than those of either of its parents, 
having, when they first appear, the velvety character and purple 
color peculiar to those of the Japanese plant, and the reddish 
spot at the insertion of the petiole with the leaf blade which 
characterizes that species. They more generaly resemble 
those of the Japanese species in shape, color and texture, while 
the pubescence which covers the lower surface is almost inter- 
mediate in character between that of the American and of the 
Japanese species. The inflorescence is much larger than that 
of the American or of the Japanese plants, being fully twice as 

