176 IMMUNITY. 



centrated solutions of pyocyanase were obtained either by evapora- 

 tion of old filtered cultures of the bacillus pyocyaneus in vacuo, or 

 by precipitation of the enzyme and subsequent solution of the pre- 

 cipitate. It should be stated that Bouchard has successfully treated 

 anthrax by injection of cultures of the bacillus pyocyaneus, and also 

 by treatment with blood serum of sheep which had been immunized 

 to the streptococcus of erysipelas, but inasmuch as cultures of the ba- 

 cillus pyocyaneus are themselves toxic, Pettenkofer very properly said 

 of this treatment : " One drives out the devil with Beelzebub." Em- 

 merich and Low hold that the pyocyanase as they have obtained it 

 is free from toxic action. They think it probable that the poisonous 

 constituents of filtered cultures of this bacillus are given off during 

 the process of evaporation in vacuo or are separated from the enzyme 

 when the latter is precipitated from old cultures. At least it ap- 

 pears that the animals which they treated with solutions of pyocya- 

 nase were not injuriously affected by the injections. Pyocyanase also 

 digests typhoid, diphtheria, pest and cholera bacilli. 



Pyocyanase, as precipitated by alcohol, forms a yeUowish-green 

 amorphous substance which is readily soluble in water, to which it 

 imparts a greenish tint similar to that possessed by cultures of the 

 bacillus. The aqueous solution is distinctly alkaline. Both Mil- 

 Ion's reagent and the biuret reaction fail when applied to aqueous 

 solutions of pyocyanase, while a violet coloration is produced on 

 heating with concentrated hydrochloric acid. When pyocyanase is 

 heated with caustic potash it becomes intensely yellow, and on the 

 addition of lead acetate a blackish deposit is formed, thus indicating 

 that this substance contains sulphur. It is an interesting fact that 

 this enzyme may be heated to 90° without loss to its bacteriolytic 

 activity, and a temperature of 98.5° reduces, but does not wholly 

 rob it of this property. Notwithstanding its great resistance to heat, 

 Emmerich and Low conclude that this substance must be classed 

 among the enzymes on account of its energetic action in very small 

 amounts. They also refer to the investigation of Wiirtz, who has 

 shown that the ferment papayotin retains its peptonizing action after 

 having been exposed to a temperature of 105°. If a small amount 

 of dry pyocyanase be placed in a tube of gelatin and be kept at 22° 

 the contents of the tube are completely peptonized within twenty- 

 four hours. It also acts energetically upon fibrin. 



Emmerich and Low conclude their first paper with the following 

 statements : (1) The fact that liquid cultures of most bacteria cease 

 to develop after a few days or weeks is due to the elaboration by the 

 bacteria of enzymes, which after reaching a certain degree of concen- 

 tration, dissolve the bacterial cells. (2) There are bacteriolytic en- 

 zymes which digest not only their own bacteria, but others as well. 

 (3) The curative action of both filtered and unfiltered cultures is due 

 to the presence in these cultures of bacteriolytic enzymes. (4) The 



