24 MICROSCOPICAL RESEARCH 



"paraffin" and the "celloidinising" processes. Under treatment with 

 paraffin, the tissues of plants and animals become infiltrated and form a 

 solid block. 



With the celloidinising process the ^aris of the specimens only are 

 surrounded, held in position and supported during the sectionising and 

 succeeding manipulations, the celloidine adhering to the section when 

 cut is treated as being a part of the section itself, and is mounted as 

 such on the finished slide. 



On the other hand paraffinised sections are fixed on the slide with 

 albumen and the paraffin dissolved out. Specimens it is intended to 

 celloidinise must have their parts so exposed as to admit of the access 

 of the celloidine, and to facilitate this operation the apejc of anthers, 

 ovaries, leaf and flower buds are cut away, the cut being sufficiently 

 low to expose all the parts it is intended to keep in situ when the 

 sections are taken (Fig. 15). 



The Celloidinising Methoa. 



1. Place the specimens in absolute alcohol for twelve to twenty-four 



hours, according to size and density of specimens; if they are 

 large the alcohol should be changed once or twice. It is 

 important that the specimens should be thoroughly dehydrated 

 before passing them on to the next process. 



2. Place the specimens in ether, allow to stand twelve hours; change 



as above, if necessary. 



3. Place the specimens in equal parts of Absolute alcohol and ether, to 



which add half an inch of Schering's celloidine chips, this will 

 dissolve in four to six hours, and penetrate the interstices of the 

 specimen. A little of the celloidine chips must be added day by 

 day until the solution becomes sufficiently concentrated to form a 



