26 STAINING REACTIONS OF BACTERIA 



TABLE l— Continued 

 Gram-Positive Organisms Gram-Negative Organisms 



20. Less readily subject to auto- and sero- 20. More readily subject to auto- and 

 lysis (Benians)§§§ serolysis 



21. Less likely to form demonstrable anti- 21. More likely to form antibodies 

 bodies in infected host (Benians)§§§ 



22. Less susceptible to quinine (Graham- 22. More susceptible to quinine 

 Smith)1f111f 



§§§y. Path, b" Bad., 23, 411. 1919-20. 

 HHH/. H>'5-. 18, 1. 1919. 



suggests that perhaps the author's figures for the exceptions in each group are too high 

 This clear-cut but not all-inclusive parallelism between gram behavior and triphenyl- 

 methane behavior is striking, in spite of the fact that an exceptional gram positive 

 organism (like the streptococcus) may be resistant and an exceptional gram negative 

 one (like M. neisseri) may be susceptible; and in spite also of the fact that within each 

 group there are quantitative differences in susceptibility to dyes. 



All the relations stated in the table are doubtless subject to similar qualifications 

 which may be summarized as follows: 



1. The division between gram positives and gram negatives is not absolute. Other 

 factors enter in. For instance, the anaerobes form a class by themselves, and, although 

 usually gram positive, may have many characteristics not shared by other gram pos- 

 itives. They are really not included in the table. Again, organisms like the acid fast 

 have peculiarities of structure which separate them chemically from others. 



2. The gram positives differ among themselves, and gram positivity does not al- 

 ways depend, in the various bacterial species, on the same mechanism. This point has 

 been established by the observations of Deussen,' and more recently by the author,^ 

 who has shown that two strongly gram positive organisms like B. anthracis and M. 

 fretidenreichi differ markedly as to the stability — and probably as to the underlying 

 cause — of their gram positivity. 



3. A very interesting and important fact has been established by a number of ob- 

 servers, that there is a group of organisms which — though gram negative — are inter- 

 mediate between the two groups in most of their other characteristics. M. neisseri, for 

 example, though gram negative is dye sensitive, falls w'ith the gram positives in opti- 

 mum H-ion test, is quite resistant to lysis by KOH as compared with other gram neg- 

 atives, and shows no cytolysis in peptic-digestion tests. There is some evidence (from 

 peptic-digestion tests) that vibrios and spirilla also occupy in some respects a mid- 

 position between the two groups. 



4. The presence of spores also somewhat complicates the situation. The author^ 

 has shown that certain dyes (acriflavine, acid fuchsin) exhibit a reverse selective bac- 

 teriostatic action when tests are made between gram positive spore-bearers and the 

 ordinary gram negative bacilli. 



'Deussen, E.: Ztschr.f. Hyg. u. Infektionskrankh., 85, 235. 1918. 



'Churchman, J. W.: Slain Technology, 2, No. i. 1927.. 



3 Churchman, J. W.: J. Expcr. Med., 37, i. 1923; ibid., 38, i. 1923. 



