4 Botanical Microtechnique 



slides, and such facilities as equipment, reagents, and time. The 

 experienced worker does not overstress the merits and applicability 

 of some one method. For example, important advances in smear 

 methods and related processes for the study of nuclear and chromo- 

 some details have replaced to some extent embedding and sectioning. 

 The whole-mount method is recognized to be entirely satisfactory 

 for many algae, fern prothalli, and similar subjects. However, micro- 

 tome sections of embedded material must be made if we wish to stuch 

 the undistiabed cellular organization of a tissue, the development 

 and arrangement of organs, or the structural relationship between a 

 fungus or insect parasite and the tissues of its host. The much- 

 maligned celloidin method must be used to keep intact a badly 

 decayed, fungus-infected piece of oak railroad tie for an examination 

 of the mycelium in the wood. In order to avoid undue emphasis on 

 any particidar method, we should recognize that each of the well- 

 established methods has its proper sphere, in which it is the most 

 effective and economical method of performing a given task. 



The sequence in which processes are arranged in this book takes 

 cognizance of the fact that the paraffin method fiunishes by far the 

 largest nimiber of slides produced for teaching and research. Certain 

 operations, such as the killing of protoplasm and the preservation of 

 fixation images, are essentially similar for smears, sectioning, and 

 whole-mount methods. The preliminary processing of material is 

 nuich the same in the several embedding and sectioning methods, 

 hi \icw of these facts, the parailin method is presented with inibroken 

 continuity of its operations. 



