458 PKEPARATION, MOUNTING, AND COLLECTION OF OBJECTS 



3. Arranging for cutting. 



4. Cutting. 



5. Flattening sections and mounting, with description of the 



best serial section methods. 



The celloidin method, further subdivided as follows : 

 Celloidin imbedding in general. 

 Hardening the mass. 

 Fixing to microtome and cutting. 

 Staining and mounting, with description of (i]>/>i-o/,,-i<it>', wild 



section methods. 



4. Preparation of hard tissues, under the following titles : - 

 Grinding and polishing sections, with descriptions of lathes. 

 Decalcificatioii. 



Desilioification. 



5. Sections dealing with 



(a) Vegetable tissues. 



(b) Staining bacteria. 



(c) Staining flagella. 



(d) Chemical testing. 



(e) Preservative media. 



(f) Cleanliness, and labelling. 



Microtomes are machines devised for the purpose of obtaining 

 extremely thin and uniform slices, or 'sections' as they arc 

 technically called, of animal or vegetable tissues, hard or soft, 

 Some of the purposes to which these are adapted will be found 

 to be answered by a very simple and inexpensive little instrument, 

 which may either be held in the hand, or (as is preferable) may In- 

 firmly attached by means of a "T-shaped piece of wood (fig. 381)) to 

 the end of a table or work-bench, or may be provided with a clamp 

 for firm attachment to the work-table, as in fig. 390. This instru- 

 ment essentially consists of an upright hollow cylinder of brass, 

 with a kind of piston which is pushed from below T upwards by a fine- 

 threaded or ' micrometer ' screw turned by a large milled head ; at 

 the upper end the cylinder terminates in a brass table, which is 

 planed to a flat surface, or (which is preferable) has a piece of plate- 

 glass cemented to it, to form its cutting bed. At one side is seen a 

 small milled head, w r hich acts upon a '-binding screw",' whose ex- 

 tremity projects into the cavity of the cylinder, and serves to com- 

 press and steady anything that it holds. For this is now generally 

 substituted a pair of screws, working through the side of the 

 cylinder, instead of one as in fig. 390. A cylindrical stem of wood, 

 a piece of horn, whalebone, cartilage, &c., is to be fitted to tl it- 

 interior of the cylinder, so as to project a little above its top, and is 

 to be steadied by the ' binding screw ; ' it is then to be cut to a level 

 by means of a sharp knife or razor laid flat upon the table. Tlic 

 large milled head is next to be moved through such a portion of a 

 turn as may very slightly elevate the substance to be cut, so as to 

 make it project in an almost insensible degree above the table, and 

 this projecting part is to be sliced off with a knife previously dipped 



