10 NORMAL HISTOLOGY. 



smoothly on a slide. In other cases we have re* 

 course to the dissociation of tissues by needles, 

 called teasing. 



Section-Cutting. In many cases we wish to study 

 the structural elements of a tissue in their normal 

 relations to one another, and in parts which are too 

 thick to permit a direct observation. In such cases 

 we have recourse to thin sections, cut from the 

 tissue by a sharp knife or razor, the tissue, if not 

 sufficiently hard naturally, being hardened by one 

 or other of the above-described methods. The razor 

 employed for this purpose should have a thin blade, 

 perfectly flat on the lower side, and somewhat con- 

 cave on the upper side, so that a small quantity of 

 fluid will lie upon it. A flat, shallow dish is partly 

 filled with alcohol, with which the surface of the 

 specimen to be cut, as well as the razor blade, 

 should be constantly covered, the blade being 

 dipped into the alcohol, and as much taken up as 

 will lie upon it. The bit of tissue being held firmly 

 in one hand, and the razor firmly but lightly in the 

 other, the sections are made by long, slow, diagonal 

 sweeps of the razor, the blade being drawn from 

 heel to tip along the tissue, and not crowded di- 

 rectly forward. Much practice is required for mak- 

 ing large, thin, and even sections, and the endeavor 

 at first should be to get thin and even sections, no 

 matter how small they may be. The razor should 

 never be allowed to get dull, its edges being fre- 



