BACTi:niAL ENZY}fES 113 



that do not retain the stain. Only pararosaniliu dyes (gentian violet, 

 methyl violet, victoria blue) form such combinations, the rosanilin 

 dyes not beinji' suitable. 



The relation of bacterial protein to Gram stainiiij,^ is shown by 

 the fact that trypsin will digest killed bacteria which are Gram- 

 negative, but not Gram-positive forms; gastric juice attacks only a 

 few Gram-positive bacteria.-^ They are also more resistant to alka- 

 lies, 1 per cent. KOH dissolving only the Gram-negative bacteria. 

 Brundy -^ considers that they are more permeable to iodin, so that a 

 more central iodin-dye precipitate occurs, and Eisenberg ^'-^ suggests 

 that lipoid-protein compounds in the surface are important, in support 

 of which is the observation that ether extraction of staphylococci ren- 

 ders them negative to Gram's method, while colon bacilli treated with 

 lecithin become positive.^" Jobling and Petersen -^-^ have also found 

 the lipoids of Gram-positive bacteria more resistant to extraction by 

 fat solvents than lipoids of Gram-negative bacteria, and Tamura^*"' 

 found that the lipoid extract contains the bacterial element respon- 

 sible for Gram staining. The first-named authors suggest a relation 

 between the high content in unsaturated fatty acids, w^ith their high 

 affinity for iodin, and the positive Gram staining. On the other hand, 

 llottinger ^°'' attributes Gram staining solely to the degree of disper- 

 sion of the nucleo-proteins, which he believes to be higher in the 

 Gram-negative forms. Benians ^^ has found that crushed Gram-posi- 

 tive bacteria are promptly decolorized, indicating that the dye and 

 the cell contents do not form an insoluble compound, but that the bac- 

 terial cell wall is the chief factor in determining Gram positiveness ; 

 presumably the iodin renders the cell membrane impermeable to al- 

 cohol. This important contribution has been confirmed, as far as the 

 staining of tubercle bacilli is concerned, by Hope Sherman,^' who 

 corroborates the finding of Benians that if the bacilli are not intact 

 they are neither acid fast nor Gram positive. The same is true of 

 yeast cells (Henrici )."-•'' 



\ BACTERIAL ENZYMES ^^ 



The metabolic processes of bacteria seem to be closely dependent 



27 Btircrers, Sehermann and Sclireiber, Zeit. f. Hyg., 1011 (70), 110; Weinkoff, 

 Zeit. Immunitat.. ] 012 (11). 1. 



28 Cent. f. 13akt., ii Abt.. 1008 (21), 62. 

 2!) Cent. f. Bakt.. 1010 (56), 10.3. 



30 Jour. Path, and Bact., 1011 (16). 146. 

 30a Zeit. phvsiol. Chem., 1014 (SO), 280. 

 30b Gent. f.'Bakt., 1016 (76), 367. 



31 Jour. Path, and Bact.. 1012 (17). 100, 



32 .Tour. Infec Bis., 1013 (12), 240. 

 32a .Tour. yiod. Pes.. 1014 (30). 400. 



33 See Fuhrniann ("Vorlosungen iiber Baktcrienenzvme," Jena, 1007) for com- 

 plete bibliography to that date. 



8 



