ZOOLOGY AND BOTANY^ MICROSCOPY, ETC. 831 



darker than the transverse sections ; cell-cavity with 

 constrictions, locally entirely absent. 



a. Hibiscus. Edges sharp or rounded ; in the first case the 



cell-cavity small, in the latter case broader and oval ; 

 middle lamella sometimes wanting ; transverse sections 

 only slightly and inconspicuously laminated. Fibres 

 of very various thickness, not usually striated longitu- 

 dinally : ends rounded, blunt and almost always 

 thickened 



b. Urena sinuata. Edges sharp ; cell-cavity very small, a dot or 



narrow short line ; middle lamella broad and very dis- 

 tinct; transverse sections not laminated. Fibres of 

 uniform thickness ; rarely striated longitudinally ; ends 

 rounded, rarely somewhat thickened. 

 II. Monocotyledons. Vessels in addition to bast-fibres ; cell-cavity 

 without constrictions. 



1. Transverse sections usually rounded, rarely polygonal ; cell- 



cavity always round ; no middle lamellse. 



a. New Zealand Flax (Phormium tenax). Transverse sections 



small, usually round, closely contiguous, polygonal 

 with rounded edges ; cell-cavity empty. Fibres thin, 

 uniform, smooth, rigid ; cell-cavity small, of uniform 

 breadth, without striation or distortion ; ends sharp. 



b. Manila Hemp {Musa textilis). Transverse sections polygonal 



with rounded edges, or roundish ; cell-cavity large, 

 roundish, sometimes with yellow contents. Fibi'es of 

 uniform thickness, smooth, not striated ; walls thin ; 

 ends sharp, or slightly rounded. After combustion 

 siliceous skeletons remain behind in the form of strings. 



2. Transverse sections evidently polygonal ; cell-cavity poly- 



gonal, with one or more sharp edges, moderately large ; 

 no middle lamella. 



a. African Hemp (Sanseviera). Transverse sections closely 

 contiguous, not laminated. Fibres thin, smooth, with 

 sharp ends. 



h. Aloe. Transverse sections not very numerous in a group ; 

 edges slightly I'ounded ; cell-cavity not very large, 

 polygonal, often with rounded ends ; large spiral 

 vessels ; fibres of uniform thickness, without structure ; 

 ends sharp or rounded. 



c. Agave. Transverse sections polygonal, bounded by straight 



lines, closely contiguous ; cell-cavity largo, polygonal ; 

 its edges less sharp. Fibres rigid, considerably broader 

 towards the middle ; ends broad, thickened, sometimes 

 split. 



3. Transverse sections polygonal, closely contiguous, small, 



bounded by straight lines ; edges very sharp ; cell-cavity 

 small, round or linear ; middle lamella very evident. 

 Fibres narrow, striated, with sharp ends : — Yucca. 



