THE MEDULLARY RAYS OF CEDRUS 
M. A. CHRYSLER 
(WITH SEVEN FIGURES) 
In those conifers the medullary rays of which are provided with 
marginal cells, it is commonly found that marginal tracheids in the 
xylem region of a.ray are conterminous with the so-called “erect 
cells” in the phloem region of the ray. Such a condition was figured 
for Pinus sylvestris by STRASBURGER in his notable contributions to 
the anatomy of the conducting system (5), and the figure is copied 
in his textbook (6). It has in fact been claimed by more recent 
writers (7) that the marginal tracheids and the erect cells are 
corresponding structures, just as are ordinary tracheids and sieve 
tubes. It was accordingly with some surprise that the writer 
observed, in the course of a study of the origin of erect cells (1), 
that in the genus Cedrus erect cells were conterminous.with paren- 
chyma cells in the xylem region of a ray. An insufficient supply 
of material was at that time available, but recently this lack has 
been liberally supplied through the kindness of Miss R. HotpDEN 
of Cambridge University, Mr. R. I. Lyncu, Director of the Cam- 
bridge Botanical Garden, Professor E. C. JEFFREY of Harvard 
University, and Mr. H. N. Lee, formerly of the same institution. 
From these sources material of all three species of Cedrus and of 
the related monotypic genus Pseudolarix has been received, and 
it is now possible to give an interpretation of the anomalous 
- features of Cedrus wood, and to offer evidence as to the relation- 
ships of the genus. 
In a general way the wood of Caarus bears much resemblance 
to that of Abies, but differs in having more numerous resin cells at 
the outer edge of annual rings, and in showing ray tracheids, which 
are, however, mixed with marginal parenchyma. Marginal cells 
are typically much less abundant than in Pinus and other Pineae; 
in Cedrus some rays lack marginal cells, while others are devoid of 
such cells for considerable distances. STRASBURGER (5) has called 
387] [Botanical Gazette, vol. 59 
