Adkins on. —Some Features of the Anatomy of the Vitaceae. 135 
The division of the Vitaceae into two sub-families, the Vitoideae and 
the Leeoideae, according to Engler and Prantl, is justified on anatomical as 
well as systematic grounds. Leea differs from the other members of the 
family, nearly all of which are vines climbing by tendrils, in the woody 
stem and the shrub or tree-like habit. In the wood of Leea (of which 
a transverse section is shown in PI. XV, Fig. 1), numerous broad rays separate 
narrow fibro-vascular bundles. The vessels are smaller relatively than in 
V. Labrusca , L., and are intercalated in the radial rows of woody elements. 
The parenchyma is vasicentric. Dividing the bundles are conspicuous linear 
rays (shown in detail in Fig. 2), the cells of which are smaller and less 
regularly rectangular than the multiseriate ray cells. Inasmuch as they are 
radially elongate and continue through the annual ring, they form a true 
uniseriate ray. 
The uniseriate ray does not normally occur in the adult stem of the 
species of Vitis examined, except in Vitis calif ornica , Benth. (the wood of 
which is shown in cross-section in Fig. 3). The vessels have reached an 
enormous development, often occupying nearly the entire width of the fibro- 
vascular bundle; the spring wood consists almost entirely of vessels, with 
a marked segregation of the woody elements at the end of the annual ring, 
and the large rays, ten cells wide, are sinuous from compression by the large 
vessels. Most plainly to be seen in the autumn wood (Fig. 4) are uniseriate 
rays which continue from ring to ring, bending about the huge vessels of the 
spring wood, sometimes compressed by vessels on both sides, as in the centre 
of Fig. 4. As in Leea , the cells of the uniseriate rays are small and rounded, 
but radially elongate. In tangential section the xylem bridges through the 
multiseriate rays appear sometimes two or three tracheides high. By the 
more frequent occurrence of these xylem bridges, the rays become elongate- 
fusiform, a condition somewhat like the marked compound fusiform rays of 
Quercus. In all respects, the wood structure of V. calif 'ornica, Benth., corre- 
sponds to the conditions found in Leea, except for the large vessels and 
broader rays, which are special adaptations to the climbing habit. 
The mature wood of V. calif ornica, Benth. differs from V. Labrusca , L. 
and ten other species examined, in the presence of two sorts of rays, a condi- 
tion strikingly similar to the ray structure of Quercus. The presence of the 
linear rays may be interpreted as the persistence of a primitive character 
which has disappeared in the other species, or as the result of reversion and 
reduction from a primitively multiseriate ray. The application of Haeckel’s 
Law of Recapitulation to the study of plant seedlings is found to explain 
accurately many difficult problems of anatomy. An examination of the 
seedling of Vitis indicates the primitive structure of the wood. Seedlings 
of V. Labrusca , L., and V. cordifolia , Michx. (Fig. 5), exhibit in stem and root 
1 Holden, R. : Reduction and Reversion in the North American Salicales : Annals of Botany, 
vol. xxvi, No. ci, p. 170, 
