60 A HALF-HOUR WITH THE 



appearance in the centre (a). The hairs of animals 

 offer a great variety in the disposition of the cells 

 of which they are composed. The hairs of the 

 mouse present a series of dark partitions running 

 across the hair between the cells. In the younger 

 hairs, these partitions are single (Fig. 180, a, PL 7), 

 but in the older ones they appear double (6). The 

 hairs from the ear of the mouse present these 

 dark partitions very distinctly (d). Such hairs 

 stand intermediate between true hair (e) and 

 wool. A piece of flannel or blanket will afford 

 a good illustration of the latter (Fig. 225, PL 8). 

 In this case it will be seen that the scales, or 

 cells, of the cortical part, project beyond the 

 surface, and render the wool rough. This rough- 

 ness of the outside renders it possible for such 

 hairs to be used in the process of felting ; the 

 rough sides of the hairs adhering together. Human, 

 and other smooth hairs, will not felt. 



The fibres of plants used in weaving may be 

 conveniently compared with hairs derived from the 

 animal kingdom. The woody fibre of the flax may 

 be obtained from a linen handkerchief (Fig. 224, 6, 

 PL 8). The apparent knots in the fibre arise from 

 injury in the uses to which the fabric has been 

 applied. The original fibres have no such frac- 

 tures (a), and are perfectly smooth. So are the fibres 

 of silk (Fig. 226, PL 8). Cotton-wool is produced 

 from the inner surface of the pod, or fruit, of the 

 cotton-plant (Fig. 227, PL 8). It becomes twisted 

 during its growth, and although not so strong as 

 linen or silk, its irregular surfaces permit its being 

 spun into a strong yarn, from which all cotton 

 fabrics are made. The young microscopist should 

 make himself acquainted with the forms of these 

 various fibres ; as, from their being so constantly 

 present in rooms where the Microscope is used, and 



