CHAPTER III 



THE PREPARATION OF TISSUES AND ORGANISMS FOR 

 STAINING AND MOUNTING STAINING AND STAINING 

 METHODS 



A SELECTED few of the numerous methods devised for the 

 preparation and staining of tissues, bacteria, etc., are here 

 given. Special methods occasionally employed will be 

 described when required. 



Preparation of Tissues 



In bacteriological work the demonstration of the bacteria 

 in the tissues is the primary object, and, therefore, 

 the elaborate methods which have been devised for fixing 

 the tissue elements are not usually required, unless it 

 be that the minuter changes in the latter are being studied. 

 The tissues should always be obtained as fresh as possible, 

 because within a few hours of death they are invaded by 

 numerous bacteria, derived from the air and from the 

 intestine, which may mask the original bacterial infection 

 and lead to serious mistakes if this source of error be not 

 carefully borne in mind. In all cases the tissue should be 

 cut into pieces of convenient size, not more than about 

 1 cm. in thickness, and organs if kept en masse should be 

 sliced. Having been thus prepared, the material may 

 be treated by one of the following methods : 



(a) Place directly in 'alcohol 1 for a week or a fortnight. 



1 Methylated spirit may usually be employed for all purposes when 

 an alcohol of not more than 90 per cent, strength suffices. // 



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