Making Sections 



12' 



Fig. 90. Cutting a hand section. The razor is drawn across the plate with gentle pres- 

 sure and the section is then washed into a stender dish. 



microtome being employed and an inner diameter slightly less than that 

 of the stem to be gripped. This hollow cylinder is split, the stem inserted, 

 and the section cut (Fig. 90). Of course, a few substances, such as cork oi 

 stiff plant stems, may be cut without any other support; these are, how- 

 ever, in the minority. 



Hardening and Fixing Materials for Cutting. Many objects that are in 

 themselves unsuitable for sectioning by hand can be rendered more suit- 

 able if they are fixed and hardened in some chemical reagent. If, however, 

 one is to go to the trouble of hardening and fixing material in a formula 

 designed to preserve the structure of the cells, it is usually worthwhile 

 going to the additional trouble of embedding the material and cutting 

 paraffin sections. It is generally sufficient for material that is to be hand 

 sectioned to be preserved in 90 per cent alcohol, a process that is equally 

 applicable to the stems and leaves of botanical specimens or to the very 

 few animal materials, such as cartilage, which are suitable for the pro- 

 duction of hand sections. 



Staining and Mounting Hand Sections. Sections are taken from the 

 knife as individual objects and are accumulated in a dish of some pre- 

 servative, usually 70 per cent alcohol. They should be treated as whole- 



