TOOLS AND METHODS OF WORK 31 



removed from the tissue by a comparatively short washing in alcohol 

 without the aid of acids ; it follows, therefore, that in all cases the 

 sections must be stained first with the primary or most permanent colour, 

 and secondly with the counter-stain, out of which they must be rinsed 

 quickly and transferred to the clearing oil as described above. 



Protoplasmic and nucleated tissue takes up stains more readily than 

 formed or dead tissue. A diffuse stain affects all the elements of a 

 preparation, while a specific stain affects only certain elements, or stains 

 some elements more deeply than others. A nuclear stain is one which 

 has a strong affinity for the nucleus, and which is retained by it 

 when all the surrounding tissue is freed from colour. 



Grenacher's formula of borax carmine and Kleinenberg's formula 

 of Hsematoxylin are diffuse stains ; whereas on the other hand Brazilin 

 and Delafield's formula of Haematoxylin are decidedly nuclear and 

 specific stains, and for permanent work are perhaps the most useful 

 stains known to us, with Safranin, Gossypimine, and Malachite green as 

 counter stains. 



Staining will vary in accordance with the nature of the tissue dealt 

 with and its prior treatment, if, for example, we prepare sections from 

 a lateral branch, one eighth of an inch in diameter, of the Lime tree, 

 collected at the end of March when the tree with all its ramifications is 

 infused with new life, they will take up the stains much more readily 

 and retain them much more persistently than if collected and prepared 

 in December when the tree is in a more or less dormant state. 



Mounting and Finishing the Slide. 



After the sections have been stained and cleared, they should be 

 allowed to stand for a short time in a thin mixture of Benzol balsam; 



