THE STAINING OF BACTERIA IN TISSUES. 105 



decolourising the bacteria as well as the tissue with 

 the acetic acid, the sections being thin, they may be 

 thoroughly rinsed in distilled water. Under these 

 circumstances the tissue is much more intensely 

 stained, and in somewhat thicker sections the bacilli 

 may be overlooked ; but they are, however, always 

 more intensely coloured than the tissue, and still stand 

 out pretty well. 



If it is desirable to cut up thin pieces of tissue with 

 the microtome, it is best to fix them with gum be- 

 tween two pieces of elder pith, and then to place the 

 piece so formed between two bits of cork j the whole 

 can then be screwed into' the clamp of the microtome. 

 The method of embedding the pieces in paraffin and 

 celloidin is not much used in bacteriological work, as it 

 is quite sufficient if the pieces of tissue are thoroughly 

 hardened. "^ 



If a microtome cannot be procured, the student soon 

 learns with a little practice to cut sufficiently good 

 sections with a razor, though of course they can never 

 be so even or so large as those cut with the micro- 

 tome. It is necessary to have an excellent razor, 

 which has been ground flat on the one side which 

 is laid on the section and concave on the other, and 

 which must be continually sharpened as much as pos- 



' Minot's microtome for cutting paraffin sections is espe- 

 cially to be recommended. 



