' 149 



bacillus I have observed, although rarely, exactly the same 

 black spheres as in Pfeiffer's bacillus; and on examination 

 of some cultures of Gram L negative rods, chosen at random, 

 spherical bodies or at any rate distally placed rounded swel- 

 lings were found on going through the preparations with this 

 point specially in view (for example in typhoid, coli, cholera, 

 and many others. Cf. Almquist (1,2)). 



The black spheres in Pfeiffer's bacillus are relatively acid- 

 fast. In a preparation stained with fuchsin they resisted 5o/ 

 sulphuric acid for 1 minute which completely decolourised all 

 the other elements. On the other hand they only partly 

 withstood 25o/o sulphuric acid for 1 minute. Whether this 

 relative acid-fastness is only due to the large amount of de- 

 posited dye or to a firmer combination it would be difficult 

 to decide. 



The spherical bodies are not artefacts produced in making 

 the dry preparations, as they could also- be observed in moist 

 unstained preparations (suspension in salt solution). 



The spherical bodies are not artefacts produced in making 

 currence of these bodies is no reason for believing they were 

 not present in their material. Apart from 1 the cases where 

 they were especially well-developed the fact had evaded my 

 own attention until the spring of 1921 when T undertook a 

 systematic search of several hundred preserved preparations 

 with the particular object of determining whether a classifi- 

 cation of Pfeiffer's bacillus could be made on the basis of the 

 presence or absence of granules. To my surprise I found 

 that with perhaps one or two exceptions they could be demon- 

 strated in any preparation whatever. The fact they are not 

 present in the majority of the illustrations is because they 

 are often very scanty. 



As regards the further behaviour of Pfeiffer's bacillus 

 towards stains, only the following need be noted: All the 

 strains I have examined are decolourised very easily by Gram's 

 method. The most distinct pictures are obtained by staining 

 by carbol-fuchsin (1 -f 9) for 5—10 minutes. Methylene blue 

 in alkaline solution also stains well, but an ordinary watery 

 solution of methylene blue, carbol-toluidin blue, and neutral 

 red give less clear results. 



