HAIRS NAILS. 189 



Preparation 10. The fibrous part of a hair can 

 be broken up into its constituent fibres and cells, if 

 it be first steeped for a time in strong sulphuric 

 acid. 



Preparation 11. The relative proportion of the 

 three constituent parts of a hair to one another is 

 best shown in transverse sections. 



To obtain sectio'ns of hairs, the simplest plan is to 

 tie a number together and dip the bunch into a 

 strong gum, and when this has thoroughly soaked 

 in amongst the hairs to remove the bunch and either 

 let the gum dry and harden by exposure to the air 

 or plunge it into spirit containing a little water, by 

 which in a few hours the whole mass is rendered 

 hard. Sections are then made with a sharp scalpel, 

 and are placed on a slide in water and covered. The 

 water dissolves the gum away, and all that is now 

 necessary in order to make the preparation complete 

 is to. allow a drop of glycerine to diffuse under the 

 cover-glass, which may then be secured as usual. 



The hair-follicles and roots of the hairs are seen 

 in the sections of skin. 



Preparation 12. The nails are studied by means 

 of vertical sections made both longitudinally and 

 transversely. The finger (or toe) should if possible 

 be previously injected, and the nail with the matrix 

 and surrounding skin, having been removed, may 

 be hardened either in spirit or by the spirit and 

 chromic mixture. When ready for cutting, the 

 piece should first be bisected longitudinally ; and 

 one of the halves having been embedded in a wax 

 and oil mixture, with rather an excess of wax, so as 

 to render it harder than usual, one or two longitu- 

 dinal sections (which need not be very thin) a'long 

 the whole length, to show the general relation of the 

 nail to its matrix and to the epidermis, are to be 

 made with a sharp strong scalpel. These need not 

 be stained ; they may be mounted either in glycerine 

 or, if injected, in dammar; they are intended only 

 for examination with a low power. The other piece 



