‘ Sanios Bars' in Pimis Inops , 423 
line from circular to oval, sometimes the opening being obliterated owing to 
its lateral walls coming together (Fig. 3, D to F). 
An attempt was made to find out whether any substance was present 
in the cavity of the bar ; protoplasm, cellulose, and fungal hyphae stains 
Fig. 3. Series ol tangential sections passing from cambium through the tracheides, showing 
change of shape and variations of thickness in the bar whilst passing through various parts a-f. x 390. 
a, in cambial region ; b and c, in tracheides near cambium ; d-f, in successively more remote 
tracheides. 
were used respectively, but in no case was it found possible to demonstrate 
any substance present. 
Tracing the bar outwards from a distance of two or three tracheides 
from the cambium, it was noticeable that, as the neighbourhood of the 
cambium was reached, the bar became slender with a smaller lumen and 
Fig. 4. Series of tangential sections, showing bar in section in cambium and through the two tra- 
cheides nearest to cambium, x 390. A and B, in xylem elements ; C, D, E, in cambial elements. 
thinner walls, and frequently in the tracheides nearest to the cambium 
small masses of protoplasm were often found attached to the bar laterally 
(Fig. 3, B ; Fig. 4, C). 
Passing through the cambium with the bar in section, the bar becomes 
reduced to a small dot showing no hollow in its centre ; if a hollow is present 
Gg 
