EXAMPLE 11 



Preparation of a Transverse Section of a Root, 



Using the Acid Fuchsin-Iodine Green 



Technique of Chamberlain 



This is the simplest of all the preparations described in this part of the 

 text and can be recommended unhesitatingly to the beginner who has 

 never previously prepared a section of any type. This preparation is de- 

 signed to show only the skeletal outlines of the cells and is not intended 

 to demonstrate in any way their cytological contents, which are removed 

 in the course of preparation. If cytological detail in a botanical section is 

 required, a paraffin section should be prepared and stained by the method 

 given in Example 13. 



It does not matter from what source the root is obtained, but it is recom- 

 mended that the beginner select some soft root of about % in. or some- 

 what less in diameter. If the root is collected from a living plant, it should 

 be washed thoroughly to remove any adherent sand grains, which will 

 spoil the edge of the cutting knife, and then preserved in 96 per cent 

 alcohol until required. The 96 per cent alcohol should be changed as it 

 becomes discolored, but with this precaution the specimens may be pre- 

 served indefinitely. 



It is even possible to make preparations of this type from dried roots 

 that have been preserved in a herbarium. The best reagent for swelling 

 and softening these dried preparations is a 10 per cent solution of phenol 

 in lactic acid. The lactic acid employed is the ordinary commercial solu- 

 tion in which the phenol should be dissolved immediately before it is 

 required. Pieces of the dried root are placed in a reasonably large volume 

 of this material and heated over a low flame to a temperature of about 

 50° C. Within 10 or 15 min a completely dried herbarium specimen will 

 have become swollen out to its normal size and softened to the extent 

 that sections may be cut readily from it. 



The method of sectioning selected does not particularly matter. Since 

 the sections cannot in any case be subjected to the first process while 

 they are attached to the slide, there is no real advantage in embedding 



210 



