GENER.VL TECHNIC 17 



Egg albumen, 50 c.c. 



Distilled water, 150 c.c. 



Saturated solution sodium salicylate (made 

 slightly alkaline with lithium carbonate) 50 c.c. 



(or sufficient to completely dissolve the albumen). 



Sections from material previously fixed are transferred directly 

 from the microtome to the albumen solution. Sections from fresh 

 material are placed for three to five minutes in 5- to lo-per-cent. 

 formalin solution before being transferred to the albumen solution. 



From the albumen solution sections are floated on a slide or 

 cover-glass, the excess of solution drained off and the section firmly 

 blotted with several thicknesses of washed cheese-cloth. The slide 

 or cover-glass is next immersed in alcohol or in equal parts alcohol 

 and ether to coagulate the albumen, thus fixing the section to the 

 glass. The section may now be stained and mounted in the usual 

 way. 



In the celloidin method the section is transferred from the micro- 

 tome to water, floated upon a slide, blotted with filter paper, flooded 

 with absolute alcohol and drained. Before the alcohol dries the 

 slide is flooded with a very thin celloidin solution which is immediately 

 drained off. The celloidin is then allowed to harden a moment 

 and the slide immersed in water. The section is now fixed to the 

 slide and may be stained and mounted as usual. 



VII. Staining 



This is for the purpose of more readily distinguishing the different 

 tissue elements from one another by their reactions to certain dyes. 



Based upon their action upon the different tissue elements, stains 

 may be classified as (i) nuclear dyes, which stain nuclear structures; 

 and (2) plasma dyes, which stain the cell body or cytoplasm. Plasma 

 dyes, also, as a rule, stain the intercellular tissue elements, and are 

 therefore known as diffuse stains. 



The dyes most frequently used for staining tissues are : 



I. Nuclear dyes: (a) Haematoxylin and its active principle, 

 haematein; (b) carmine and its active principle, carminic acid; (c) 

 basic anihne dyes. 



II. Plasma dyes: (a) Eosin; (b) neutral carmine, (c) picric acid; 

 (d) acid aniline dyes. 



I. Nuclear Dyes. — (a) Hematoxylin. 

 I. Gage^s Hcematoxylin. 



