xxxvi INTRODUCTION. 



METHODS OF CUTTING SECTIONS. 



IT is of the utmost importance that the student should thoroughly master the details of 

 cutting sections by hand, and also with the aid of certain instruments called microtomes. 



I. SECTIONS OF UNHARDENED TISSUES. 



If it be desired to examine only a small piece, snip off a thin fragment with a pair of 

 scissors curved on the flat, or cut off a slice with a Valentine's knife. 



II. SECTIONS OF HARDENED TISSUES. 



I. Cutting sections by hand with a razor. Tissues hardened by any of the above-mentioned 

 methods are difficult to cut unless they are clamped or imbedded in some easily cut material, 

 which must have nearly the same consistence as the tissue itself. As to the kind of razor or 

 knife to employ, the ' army razor ' answers admirably, though some prefer specially constructed 

 knives, which, I believe, possess no advantages, whilst others prefer the razor to be ground 

 flat on the side directed towards the tissue to be cut. 



If the piece of tissue be sufficiently large, seize it between the thumb and fore-finger of the 

 lg|ft hand. Hold the fore-finger horizontally, so that its outer surface forms a rest on which 

 the blade of the razor may glide. Keep the handle of the razor in a line with the blade, and 

 hold it firmly in the right hand. Draw it (from heel to tip) through the tissue towards 

 yourself. Keep the razor -well wetted with spirit, and float the section off into spirit or water, 

 with a camel-hair pencil. It requires very considerable practice before one becomes expert at 

 making sections of sufficient thinness to be of use. The razor must be kept perfectly sharp, 

 and after making a few sections should always be ' stropped.' 



If the tissue be too small or too delicate to hold in the hand, it must either be clamped or 

 imbedded in some substance. 



(a) A piece of amyloid or waxy liver, or the liver of a pig hardened in alcohol, serves the 

 purpose admirably. Make a slit in the piece of liver, and clamp the tissue in it, and cut both 

 liver and tissue as directed above. 



(b) Carrot or elder-pith may be used instead. Make a slit in the carrot or pith, and clamp 

 in it the tissue to be cut. 



IMBEDDING MIXTURES. 



(a) Melt together with the aid of a gentle heat four parts of ordinary solid paraffine with 

 one of pure lard. A quantity of this mixture should be kept ready for use. When required, 

 the mixture is to be dissolved in a vessel heated in a water-bath at the lowest temperature 

 possible. 



