OE MICROSCOPIC OBJECTS. 15 



bone, &c., and rendering them plastic. Very thin lamin of 

 these substances may also be procured by the employment 

 of a well-sharpened scraper, such as that used by cabinet- 

 maters. This plan applies more to longitudinal than to 

 transverse sections ; yet even the latter may be obtained by 

 fixing the object while soft in a piece of hard wood, and 

 scraping both together. Long continued slow boiling softens 

 and eventually disintegrates nearly all animal and vegetable 

 tissues. Muscular fibre and many other textures may thus 

 be isolated, such as spiral vessels, &c., in vegetables. 



Prolonged maceration in water, for the preparation of 

 anatomical structures, generally bony, is a process too well 

 known to need description here. The addition of very 

 dilute nitric, hydrochloric, and acetic acids is much em- 

 ployed for the separation of muscular fibres, both striated 

 and smooth. Two or three days are required, or even more. 



Nails may be softened very quickly by hot concentrated 

 eulphuric acid or, still better, by liquor potassse, strength 

 about 25 to 27 per cent. so as to show isolated and dis- 

 tended cells by solution of the intercellular substance. 



Bones are softened, i.e. decalcified, by boiling or, still 

 better, by slow maceration in weak solutions of nitric and 

 hydrochloric acids, by the action of which the phosphate 

 and carbonate of lime may be entirely removed. This pro- 

 cess isolates the animal matter, i.e. the osseine sometimes 

 miscalled gelatine with all its peculiar fibres and processes. 

 But bones may be treated in another way, so as to show or 

 isolate the bone corpuscles with their processes, by removal 

 or destruction of the intercellular substance. Though this 

 can scarcely be called softening them, yet it may be most 

 fitly mentioned here. For this purpose, a Papin's digester 

 is necessary. When the boiling of bones has been for a long 

 time carried on by means of one of these machines, they 

 seem to be dissolved ; but on examination a coarse powder, 

 consisting of the isolated corpuscles and their processes, is 

 found at the bottom of the vessel, which will amply repay 

 the trouble of examination. 



