10 PRACTICAL BOTANY 



of the special methods of preparation of objects for cutting by 

 the microtome, nor of the different forms of microtome, or the 

 way in which the microtome is to be used. 



When cutting sections the razor is to be opened so 

 that the blade is in a line with the handle : the object to 

 be cut may be held in the thumb and first finger of the 

 left hand, while the razor is grasped firmly by the four 

 fingers of the right : it may be found convenient to 

 rest the thumb of the right hand on that of the left so 

 as to regulate the movements of the right hand. The 

 edge of the razor is not to be rudely forced through the 

 tissues of the specimen, but a sliding cut is to be made, 

 thus using a considerable length of the edge of the 

 razor : in this way a smoother surface of section is 

 obtained, and the tissues are not displaced as they 

 otherwise might be. 



Care must be taken to keep the object and the razor 

 wet during the process of cutting, in order to avoid the 

 entrance of air into the tissue, and to prevent adhesion 

 of the section to the razor. When fresh material is cut, 

 water or very dilute alcohol may be used for this 

 purpose, but if material which has been hardened is cut, 

 it is advisable to use alcohol of the same strength as 

 that in which the material has been preserved. 



IV. Embedding. The objects are frequently so 

 large that they may be held in the hand whilst they are 

 being cut. If they are too small for this, it is con- 

 venient to embed them in some substance. 



The simplest method is to fix the object into a slit in 

 a piece of pith. Dried elder-pith is the best, and it 

 may be bought ready prepared from the dealers. 



When the sections are to be made with a microtome 



