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Kisch. — The Physiological Anatomy of 
or less oblique, may readily be understood by means of cutting small 
models. Thus sections, without departing far from the radial, may cross 
from one file into another with end walls at a different level, or, if somewhat 
transverse, may cut across the side instead of the end walls, making the cells 
appear comparatively short (see Text-fig. 16, c). 
In tangential section the periderm cells, as already stated, are commonly 
narrower, and their ends more pointed than in radial view (see Text-fig. 17). 
It is from tangential sections that the heterogeneous nature of the cells in 
certain periderms, which will be referred to later (p. 304), becomes at once 
apparent. 
(3) Character of the Radial Files. 
The cells of one radial file generally alternate with the contiguous 
cells of the files on either side, and frequently also with those above and 
Text-fig. 10. Diagrammatic transverse sections showing short files in the periderm. A, Lepi- 
dodendron Hickii. Will. Coll., 380 b. B, Sigillaria scutellata . U. C. L. Coll., B 12. C, Lepido- 
dendron selaginoides. U. C. L. Coll., A 01 2. x 265. 
below. Haberlandt showed that in cork the former arrangement facilitated 
stretching in the tangential direction, 1 while according to the same authority 
great additional strength is given to prosenchymatous tissues by the close 
interlacing of their pointed ends. 2 
Typically in transverse section each radial file extends throughout the 
width of the periderm, but most preparations show frequent exceptions 
1 Haberlandt ( 13 ), p. 127, 4th ed. 2 Loc. cit., p. 142. 
