78 



THE MICROSCOPIST. 



manner in which the threads or bundles of fibres are woven or 

 interlaced. For this purpose they should be examined as 

 opaque objects on a black ground, with a magnifying power 

 of from 30 to 60 diameters. The fibres of cotton are readily 

 distinguished under the microscope from those of linen, wool, 

 &c. Cotton fibres are tubular, and are formed' of pure cellular 

 tissue. These tubes, from the thinness of their sides, often 

 collapse and appear like flat ribbons or bands. The reason 

 assigned for the preference given to linen (flax) over cotton 

 for lint, for surgical purposes, is that the fibres of the former 

 are solid cylinders of woody fibre, while the edges of the 

 flattened bands of the latter are supposed to irritate the 



rig. 27. 



wounds. Fig. 27 exhibits the different appearance of these 

 fibres under the microscope; a, fibres of flax; b, cotton fibres; 

 c, filaments of silk ; d, wool of sheep. 



Circulation in Vegetables. The circulation in plants, termed 

 cydosis, is a revolution of the fluid contained in each cellule, 



