98 ELEMENTS OP /iPPLIED MICROSCOPY. 



ity of the cells are straight or bent or curled, markings, 

 size and character of the central canal, if any. Polarized 

 light is often of great service in the identification of paper 

 fibres. 



4. Analytical Key to Paper Fibres. — ^The authors 

 above mentioned suggest the following useful key for 

 the preliminary examination of paper. In this table 

 the word fibre is restricted to those cells which are very 

 long in proportion to their breadth. 



ANALYTICAL SCHEME. 

 A. Fibres are characteristic; other characteristic forms absent. 

 I. Fibres are long; greater than diameter of field (Mag. = 60). 

 (i) Fibre has many joints, knots, or projections,, especially 

 by polarized light, 

 (a) Fibre is fine; quite smooth; joints not very notice- 

 able. 

 Paper mulberry — Manila hsmp — Agave. 



(5) Fibre is coarse; uneven; joints are large and promi- 



nent. 

 Linen — Jute — Hemp {Cannabis saliva), 

 (c) Fibre shows overlapping scales. 

 Wool. 



(2) Fibre has peculiar markings; dotted, circular, square, 



net-like. 

 (a) Markings resemble circular or square perforations. 

 Spruce (fir, hemlock, tamarack, balsam) — Pine — 

 Redwood — Red cedar — Arbor vitce — Cypress. 



(6) Markings net-like, "feather-stitch," spiral. 



Redwood — Cypress — Banana (Jruit- stem)— 

 Ramie. 



(3) Fibre is smooth and regular. 



(a) Many fibres resemble twisted ribbons. 



Cotton — Banana {stalk and leaf-stem). 



(b) Fibres are round, cylindrical. 



Silk — Sisal hemp — Bark 0} cotton'Stalk. 



