1914] 



WINTON— HISTOLOGY OF FLAX FRUIT 



447 



Perrot (loc. cit.) describe crystals in this layer, but the writer 

 finds them in an interesting tissue below the epicarp. 



Crystal cells (cr). — -Resting on the hypoderm and more or less 

 separated by its projections is a strikingly characteristic tissue one 

 cell in thickness, consisting of isolated compressed spherical or 

 lens-shaped cells arranged in indistinctly longitudinal rows. The 

 light brown inner and side cell walls are so thickened that the cell 

 contents, consisting of a single monoclinic crystal (about 13 ju), 

 completely fill the lumen. 

 On sectioning, the crystal 

 usually escapes through the 

 thin outer wall. 



The hypoderm (hy 1 and 



hy 2 ) 



is yellowish in color, 



pitted, and greatly thickened, 

 with numerous projections 

 of the outer wall pushing up 

 under and between the 

 isolated crystal cells. In 

 tangential sections through 

 the outer walls these pro- 

 jections (fig. 3, hy 1 ) appear 

 like another layer of small, 

 more or less spherical cells. 



The cells are transversely Fig. 4.— Dissepiment in surface view; X 160 



elongated over the greater 



part of the valve, changing abruptly to a longitudinal arrange- 



ment at the sutures. 



The mesocarp (mes) varies greatly in thickness. At the thin 



lacking, but becomes 



mass 



of cells along the juncture with the dissepiment. The cells 

 have slightly thickened pitted walls, except those adjoining the 



hypoderm, which may 



e thicker. Cell contents are usually lack- 

 small starch grains are present indicating 



maturity 



Endocarp 



ingle layer of pitted, strongly elongated 

 in groups, is similar to the epidermis of 



