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A. Making Preparations 



I. Preservation of Material, In many cases it is 

 possible, and even preferable, to use fresh material, but 

 it is often convenient to keep it for a time, since many 

 of the specimens required are only to be obtained 

 at certain seasons of the year : the best liquid for this 

 purpose is ordinary methylated alcohol, in such 

 quantity as completely to cover the material. It must 

 be remembered that this will extract the green colour- 

 ing matter (chlorophyll) from the material immersed in 

 it, as well as resin and other substances. 



II. Hardening.. It is not necessary, for the general 

 study of the histology of the mature parts of plants, to 

 harden them, for the tissues are usually sufficiently firm 

 to admit of their being cut satisfactorily. In the case 

 of young, or of exclusively parenchymatous tissues 

 especially those of non-vascular plants, it is necessary, 

 to harden them, and for this purpose alcohol may 

 be used. 



When it is desired to study the structure of the 

 protoplasm, and of the nucleus, special methods must 

 be employed for hardening them, or rather for fixing 



