88 THE MICROSCOPE. 



pressed, and worked together between damp cloths. 

 The same property enables woven woollen tissues to 

 become close and thick ; every one knows that worsted 

 stockings shrink in their dimensions, but become much 

 thicker and firmer, after they have been worn and 

 washed a little; and the ' stout broadcloth' which has 

 been the characteristic covering of Englishmen for 

 ages, would be but a poor open flimsy texture but for 

 the intimate union of the felted wool-fibres, which 

 accrues from the various processes to which the tabric 

 has been subjected. 



" In a commercial view, the excellence of the wool 



Hair of Larva of Dermestes. 



is tested by the closeness of its imbrication. When 

 first the wool-fibre was submitted to microscopical 

 examination, the experiment was made on a specimen 

 of merino : it presented 2,400 serratures in an inch. 

 Then a fibre of Saxon wool, finer than the former, and 

 known to possess a superior felting power, was tried : 

 there were 2,700 serratures in an inch. Next a speci- 

 men of Southdown wool, acknowledged to be inferior 

 to either of the former, was examined, and gave 2,080 

 serratures. Finally, the Leicester wool, whose felting 

 property is feebler still, yielded only 1,850 serratures 

 per inch. And this connection of good felting quality 

 with the number and sharpness of the sheathing scales 

 is found to be invariable." 



The hairs of insects, caterpillars, &c., are of infinite 

 variety of form. The hairs of the larva of the bacon 

 beetle (Dermestes} are of two kinds : in one, the shaft 

 is covered with minute spinous secondary hairs closely 



