354 



THE MICROSCOPE. 



quence of the outer membrane containing more lignine. 

 It is important to the manufacturer that he should be 

 able to determine the true character of some of the textures 

 of articles of clothing, and this he may readily do with the 

 microscope. In linen we find each component thread made 

 up of the longitudinal, rounded, unmarked fibres of flax ; but 

 if cotton has been mixed, we recognise a flattened, more or 

 less twisted band, as in fig. 196 b, having a very striking 



resemblance to hair, which, in 

 reality, it is ; since, in the condi- 

 tion of elongated cells, it lines the 

 inner surface of the pod. These, 

 again, should be contrasted with 

 the filaments of silk, fig. 196 A, and 

 also of zvool, fig. 197 a. The latter 

 may be at once recognised by the 

 zigzag transverse markings on its 

 fibres. The surface of wool is 

 covered with these furrowed and 

 twisted fine cross lines, of which 

 there are from 2,000 to 4,000 in 

 an inch. On this structure de- 

 pends its felting property. In 

 judging of fleeces, attention should 

 be paid to the fineness and elasti- 

 city of the fibre, — the furrowed and scaly surface, as shown 

 by the microscope, — the quantity of fibre in a given surface, 

 the purity of the fleece, upon which depend the success of 

 the scouring and subsequent operations. 



In the mummy-cloths of the Egyptians, flax only was 

 used, whereas the Peruvians used cotton alone. By recent 

 improvements introduced into the manufacturing pro- 

 cesses, flax has been reduced to the fineness and texture of 

 silk, and made to resemble other materials. 



Silk is secreted from a pair of long tubes ending in 

 a pore of the under-lip of the silkworm. Each thread is 

 made of two filaments coming from these, and they are 

 glued together by a secretion from a small gland near. 

 The quality of the silk depends on the character and 

 difference of the two secretions. 



All woody fibi-e is made up of elongated cells, generally 



Fig. 197. 



Wool of Sheep, b, Fila- 

 ments of Flax. 



