INVESTIGATIONS ON HARMFULNESS. 55 



in a concentration of 1:100,000 killed them, whereas strychnin 

 nitrate in the same concentration is substantially without effect. 

 Death is caused by absorption of the dye by the albumen of the 

 protoplasm. The dyes seem to be absorbed not only by living albu- 

 men, but also by living nerve cells and fibers. Pure anilin or coal- 

 tar colors, however, are not poisonous in the ordinary meaning of the 

 words, that is, humans are not likely to be easily injured by them. 



Houghton (J. Amer. CTiem. Soc., 1907, v. 29, pp. 1351-1357} shows 

 that Bismarck Brown (197, 201) and Crocein Scarlet (160?) hinder 

 the peptic digestion of fibrin, casein, and albumen. 



Stilling (Anillnfarbstoffe als Antiseptica, 1890, v. 2, pp. 55-56) states 

 that he found the animal cells to be affected by pure coal-tar colors 

 in the same way that vegetable cells were affected. 



Penzoldt, based upon the experimental work of Beckh (Archiv. 

 Exp. Path. Pharmak. 1890, v. 26, p. 310), reports as follows: 



Of the 15 dyes- 

 Green Table 

 Name. number. 



1. Malachite Green 427 



2. Hofman's Violet (methyl variety) 450 



3. Methyl Violet 451 



4. Rose Bengal (Erythrosin) 517 



5. PhenylBlue 480 



6. Methylene Blue 650 



7. Fuchsin 448 



8. Coralline '. 484 



9. Eosin 512 



10. Methyl Orange 87 



11. Vesuvin 197 



12. Tropaeolin 88 



13. Scarlet Red (?) 



14. Congo Red. . . 240 



15. Indulin sulpho acid 601 



all of which are water soluble and when used were free from arsenic, only the first six 

 in saturated solution arrested the development of Staphylococus pyogenes aureus, and 

 of these six all but the Erythrosin and Methylene Blue arrested the growth of anthrax 

 bacillus. 



Of these six when injected into rabbits subcutaneously the following produced no 

 changes of consequence: Erythrosin (250), Phenyl Blue (100), Methylene Blue (75). 

 The numbers in parentheses show the number of milligrams of dye per kilo body 

 weight of the rabbits. 



Methyl Violet (50) produced only local changes, such as gangrene. 



Malachite Green (100) and Hofman's Violet (20) produced muscular paralysis, which 

 in the case of Malachite Green resulted fatally on the ninth day; in the case of Hof- 

 man's Violet the paralysis was complete on the tenth day. 



The remaining nine colors are apparently of no effect upon staphylococus or upon 

 anthrax. 



H. W. Williams (A Manual of Bacteriology, 1906, p. 200), under 

 "Disinfectants and Germicides," says: 



Aniline dyes. Many of these substances, notably pyoktanin (Methyl Violet), pos- 

 sess germicidal properties. A solution of 1:5000 will kill the anthrax bacillus in two 



