100 PREPARATION AND MOUNTING 



when cut transversely, strongly resembles those of the third and 

 softer formation. All these are best seen when .mounted in Canada 

 balsam, but care must be taken that they have been thoroughly 

 dried after cutting, and then steeped in turpentine. 



An interesting object may also be procured from whalebone by 

 cutting long sections of the hairs of which it is composed. Down 

 the centre of each hair we shall find a line of cells divided from 

 one another very distinctly. And (as recommended in the " Mi- 

 crographic Dictionary ") if whalebone be macerated twenty-four 

 hours in a solution of caustic potash it will be softened, and by 

 afterwards digesting in water, the outer part will be resolved into 

 numerous transparent cells, which will show more plainly the 

 structure of this curious substance. 



In a former chapter, hairs were mentioned, their many and in- 

 teresting forms, and their beauty when used with polarized light. 

 The sections of them, however, are no less a matter of study, as 

 this mode of treatment opens to sight the outer " casing," and 

 the inner substance somewhat resembling the pith of plants. 



It would be out of place to enter into the description of the 

 different forms met with ; but the ways in which sections are to 

 be procured may be glanced at. If transverse sections are required, 

 some place a quantity of hairs betwixt two flat pieces of cork, 

 which by pressure hold them firmly enough together to allow the 

 required portions to be cut with a razor. Others take a bundle 

 of the hairs and dip it into gum or glue, which gives it when dry 

 a solidity equal to wood. Sections of this are then cut with the 

 machine mentioned a little further on, and these may be mounted 

 in balsam. The human hair is easily procured in the desired sec- 

 tions by shaving as closely as possible a second time and cleansing 

 from the lather, &c., by carefully washing. Most hairs, however, 

 should be examined both transversely and longitudinally. It is 

 not difficult to procure the latter, as we may generally split them 

 with the aid of a sharp razor. In a great number of hairs there 

 is a quantity of greasy matter which must be got rid of by soak- 

 ing in ether or some other solvent before mounting. 



We may next consider the best method of procuring sections of 

 wood, which must be cut of such a degree of thinness as to form 

 transparent objects, and so display all the secrets of their struc- 



