82 MISSOURI BOTANICAL GARDEN. 
spring growth neither large nor numerous, and the medul- 
lary rays invisible to the naked eye.* The occurrence of a 
single broken row of vernal ducts somewhat larger than those 
of the rest of the year’s growth, the oblique position of the 
groups of the latter, and the absence of loose parenchyma- 
tous bands, suggest a comparison with Aster argophyllus, 
certain species of Ulmus and Celtis, and, particularly, 
Daphne Mezereum.t Except for the absence of coarse 
parenchyma bands, it also resembles somewhat the wood of 
Ailanthus, Hippophae, and numerous Leguminosae, though 
in these the vernal ducts are usually larger and more numer- 
ous, and the secondary thickening of the medullary rays 
and the libriform cells is far more marked. 
The cortex of Leitneria, which, as has been stated 
above, is rich in tannin, is rather thin, and consists at first 
of fundamental parenchyma, which is collenchymatously 
thickened, with large often transversely elliptical pits, for 
about eight layers of cells immediately below the epidermis, 
and passes into a like number of thin walled cells by a tran- 
sition through about three layers, while between this primary 
cortex and the cambium an abundant secondary cortex is 
developed, containing large fan-shaped abundantly crystal- 
liferous dilatations of the principal medullary rays, between 
which lie broad wedges of bast. Except for a few small 
and scattered bundles of hard bast fibers in the pericycle, 
at the inner border of the primary cortex close beneath the 
collenchyma, none of the bast fibers become thick walled, 
but they remain as long wide generally irregularly collapsed 
tubes with oblique often clustered simple pits, and destitute 
of protoplasm. Traversing these bast wedges are a few 
secondary rays, while tangentially they are parted by plates 
of thin walled parenchyma cells from two to about five 
times as long as broad, with horizontal septa, a few rows 
of which contain crystals; and among these cells, rich in 
* Hartig, Timbers and How to Know Then, 8. 
+ From an examination of Nordlinger’s set of 1100 cross-sections of 
woods.— Cf. p. 78 of text accompanying century xi. 
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