CHAPTER XI 



FIXING AND THE PRESERVATION OF TISSUES, ORGANS, AND 

 ENTIRE ORGANISMS. IMBEDDING, SECTIONING, STAINING, 

 AND MOUNTING FOR THE MICROSCOPE. SERIAL SECTIONS. 

 MODELS 



600. Apparatus and material for Chapter XI. 



1. Bottles and vials for specimens 9. Hones and strops for sharpen- 

 and tissues (fig. 196-197, 211-214). ing knives. 



2. Dissecting instruments. 10. Slide trays or cylinders for 



3. Fixing agents and alcohol. ribbons of sections (fig. 206-207). 



4. Washing apparatus (fig. 216- n. Slides and cover-glasses. 

 217). 12. Slide baskets and glass-stop- 



5. Clearing agents and imbedding pered jars (fig. 231-232). 



material. 13. Staining liquids and mounting 



6. Infiltrating oven and spreading media. 



plate (fig. 219-220, 226-230). 14. Modeling material, wax and 



7. -Section razors and knives (fig. blotting paper. 



218,223). 15. Apparatus for drawing sections 



8. Microtomes. for models ( 671-681). 



601. Fixation and preservation of organs and tissues. By 

 fixing or fixation in histology is meant the preparation of fresh tissues, 

 organs, embryos or small adult animals usually by means of some 

 chemical mixture, called a "fixer," so that the organ, etc., as a whole 

 and the elements or cells composing it shall retain as nearly as possible 

 the morphologic characters present during life. The more perfect 

 the fixer the nearer will be the preservation of all structural details. 



Unfortunately no single "fixer" preserves with equal excellence all 

 the structural details, and therefore it is necessary to prepare the 

 fresh tissue in several different ways and to make a composite of the 

 structural appearances found, thereby approximating the actual struc- 

 ture present in the living body. Changes are so rapid after death 

 that the fixation should begin as soon as possible. For the most 

 perfect fixation the living tissue must be put into the fixer. 



With one of the larger animals where the whole animal is to be 



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