1g1I] HEMENWAY—PHLOEM OF JUGLANDACEAE 133 
Fig. 3 is a high-power view of a part of that shown in fig. 2. 
On the left side there is again a good view of crystal-bearing phloem 
parenchyma cells. In the center there is a large sieve tube with 
lateral sieve plates covering the entire tangential wall. These 
lateral sieve plates when appropriately stained are found to be 
filled with angular pits with a fine netlike mesh between. They 
appear to be exactly the same as the terminal sieve plates. 
Fig. 4 is a radial section of Carya glabra, stained with Russow’s 
callus reagent. At the top and bottom are shown in face view 
terminal sieve plates covered with callus. Between these two 
sieve tubes are the dark spots of callus on the lateral sieve plates 
in cross-section. 
Fig. 5 is a view similar to fig. 4. On the right is a portion of a 
ray showing the parenchyma cells with patches of dark-stained 
starch grains. On the left is again seen some phloem parenchyma 
cells containing large crystals. 
Fig. 6 shows the center portion of fig. 5 more highly magnified. 
The dark dashes along the center are cross-sections of the deeply 
stained lateral callus. The writer has counted 40-50 of these 
in a straight line along the side of a large sieve tube. 
Carya has relatively larger sieve tubes than Juglans or Ptero- 
carya. In cross-section they are as much larger than the other 
elements of the tissue as medium sized vessels of the xylem are 
larger than the tracheids. 
The phloem of Juglans and Pterocarya is much like that of 
Carya, but there are a few general characteristics by which they 
may be readily separated. The crystal-bearing phloem paren- 
chyma cells of Juglans cinerea and Juglans nigra are nearly cubical, 
and each contains a druse, while those of Carya are longer than 
wide and contain prismatic crystals. Juglans nigra has very 
many crystals, especially in specimens from the trunk of large trees. 
Besides the crystals in the parenchyma, the bast fibers are often 
filled with rows of cubical crystals. These bast fibers of Juglans — 
nigra occur in widely interrupted rings, while in Juglans cinerea 
the rings of bast fibers are nearly continuous. The bast fibers 
of Juglans and Pterocarya are thick-walled and keep a more or less 
circular outline; while Carya has relatively much more numerous 
