TEXT-BOOK OF BACTERIOLOGY. 251 



The process is now repeated a few times, beginning- with the de- 

 coloration in potassium, always shortening the time (for instance, 

 only three or four seconds for the solution of permanganate of 

 potash), till the sections are quite colorless. Then comes alcohol, 

 oil of cloves, and xylol-Canada balsam. 



" Smeared " cover-glasses are treated in the same manner, only 

 that after the staining in gentian-violet distilled water must be 

 employed instead of pure alcohol, and the different operations must 

 be conducted more rapidly. 



Besides this method several others have been recommended 

 which claim to attain the same results more easily. We will men- 

 tion that of de Giacomi, by which cover-glasses and sections are 

 stained in anilin-water-fuchsin, which is employed hot only a few 

 moments for the former and twenty-four hours cold for the latter, 

 and then decolored with a solution of perchloride of iron, at first 

 much diluted, then quite saturated. Cover-glasses are rinsed in 

 water, sections in alcohol. The after-treatment is as usual. 



In such preparations, Lustgarten discovered peculiar rod-cells 

 which resembled the tubercle bacilli in appearance, but were de- 

 cidedly curved more frequently than the latter, and are further 

 remarkable for slight knob-like swellings inclosed singly or in 

 groups in large cells, which have no visible connection with their 

 surroundings. 



It is of course natural to attribute a special importance to these 

 bacilli, which stain in such a peculiar manner and have such a re- 

 markable position in the tissue, but we have no proof of their being 1 

 the cause of syphilis. 



In the first place, we must object to the process by which the 

 bacilli are rendered visible as being unsatisactory. It is not alone 

 extremely complicated, but its results are wanting in certainty. 

 Although Lustgarten assures us that he has regularly found the 

 bacilli in the cases he has examined, many who have wished to 

 confirm his statement have been less successful. In the cover-glass 

 preparations the bacilli are, indeed, often found, but in sections they 

 have been found only by a small number of investigators, even 

 when the instructions given were followed out with the utmost ex- 

 actitude. 



Lustgarten himself found the micro-organisms in question only 

 in very small quantities, and neither their numbers nor their posi- 

 tion and distribution in the tissue seem calculated to account for 

 the violent changes which are the peculiar result of syphilis. 



Lastly, the value of the method (and, therefore, also the import- 

 ance of the rod-cells) has been seriously doubted, sin-ce bacilli have 



