390 BOTANICAL GAZETTE [MAY 
advanced stage of degeneration of marginal cells. These “ghosts” 
are of very frequent occurrence in the three species of Cedrus. 
Another common feature of the marginal row is shown in fig. 4, 
from a root of C. libani, where a solitary cell containing rhombic 
crystals of calcium oxalate appears at the end of an annual ring, 
a situation which is quite the rule, though not invariable. Crystal- 
containing cells may also be found among the erect cells of the 
phloem region of a ray, as is shown in fig. 5. The occurrence of 
crystals in the phloem parenchyma is universal in Cedrus, as in 
oO : 
= > O°? of 
3 & ° oF 
S 5S) &, ; 
Fic. 3.—C. libani, stem; part of a ray traversing three growth rings, at the limit 
of each of which occurs a marginal parenchyma cell; 290. 
many other genera of conifers. Since calcium oxalate is an end 
product of katabolism, cells which are charged with it must be 
regarded as having passed their active or functional stage. This 
observation together with others here recorded indicate that the 
marginal cells are in process of degeneration and disappearance. 
In order to determine if possible the order of appearance of the 
structures found at the margin of a ray, serial sections of young 
stems and roots have been studied. Material of seedlings has not 
been available, so that the study has been confined to roots and 
branches of an age of six to seven years. In fig. 6 is shown part of 
