40 TEXT-BOOK OF BACTERIOLOGY. 



somewhat difficult to see these portions of the cells clearly in the 

 uncolored preparation, they now surpass everything else in dis- 

 tinctness, so that it is by the presence of the nuclei that attention 

 is drawn to the cells to which they belong. 



Now take another section, this time from the liver of a rabbit 

 which has died from inoculation with anthrax. Treat it in the 

 same way as the other; stain it for the same length of time in the 

 same anilin solution; remove superfluous color with acidulated 

 water, and put it under the microscope with a high power, and, 

 naturally, without diaphragm. The same picture as before! the 

 same indistinct, faint staining of the connective tissue, as well as 

 the other tissues; the same prominence of the nuclei. Along with 

 them, widely dispersed over the whole preparation, anthrax bacilli 

 are seen, which in the distinctness of their coloring perhaps even 

 surpass the nuclei. 



The most striking peculiarity of the anilin dyes is that they 

 stain the nuclei and the bacteria more strongly than the surround- 

 ing parts, thus giving them an isolated coloring, and it is precisely 

 because all other parts of the object remain so much less distinct 

 than the nuclei and the cells (the bodies of the cells are thrust into 

 the background) that this system of staining is so valuable for 

 u«. It seems to point out the bacteria, which we should otherwise 

 have to seek for among many other things, and possiblj' not find 

 them after all. 



It is particularly the basic anilin stains which, by differentiating 

 equally the cell nuclei and the bacteria, are so well adapted to our 

 purposes. Most of the acid anilin stains, as also carmine and 

 haematoxylon, act differently; they are chiefly "nuclei stains," and 

 leave the bacteria almost entirely'' unaffected. 



If one of these sections which has just been colored with anilin 

 violet be placed in a solution of simple carmine or picro-carmine 

 and then treated as before, the nuclei will appear distinct under the 

 microscope, the protoplasmic bodies of the cells are also clearly 

 brought out, but of the bacteria there is nothing to be seen. They 

 have not absorbed the stain at all. 



Particular attention is called to this distinction between pure 

 nucleus staining and the staining of nuclei and bacteria together. 

 Means have been found to happily utilize this distinction for pur- 

 poses of investigation. 



On what does this difference of behavior in bodies comparativelj' 

 nearly related depend ? 



We may say that in producing the stains various processes 

 probably take place. 



