IMMUNITY. 177 



production of artificiaHmmunity with filtered or unfiltered cultures of 

 pathogenic bacteria is due to the gradual formation within the body 

 of a compound of the bacteriolytic enzyme with some albuminous 

 body ; the resulting immune proteid retains the bacteriolytic activ- 

 ity of the original enzyme. (5) This combination, which takes place 

 very slowly in the animal body, may be speedily brought about by 

 chemical reagents in vitro. (6) So-called agglutination is nothing 

 more than the first stage of bacteriolytic action of enzymes. (7) 

 Immune sera manifest their bactericidal action more energetically 

 under anaerobic than under aerobic conditions, but even in the pres- 

 ence of air, the bacterial enzymes when in highly concentrated solu- 

 tion show marked bactericidal action. (8) There are bacterial en- 

 zymes which in the animal body destroy not only the bacterial cells, 

 but their toxins as well. For instance, pyocyanase protects animals 

 which have been treated with lethal doses of diphtheria toxin. (9) 

 Our experiments show that pyocyanase may be used successfully in 

 the treatment of anthrax, diphtheria, pest, etc. (10) By means of 

 artificially prepared pyocyanase-immuneproteid a high degree of im- 

 munity against anthrax, lasting for at least fourteen days, may be 

 secured. (11) A slight elevation of temperature (about one degree) 

 observed in animals with anthrax treated with pyocyanase is a result 

 of the injection of the enzyme. (12) The bactericidal action of 

 normal blood is probably due to the presence of enzymes. 



In their second paper Emmerich and Low detail the methods 

 which they have employed in the preparation of their nucleases and 

 immuneproteids. The organism whose enzyme is desired is grown 

 in a medium which is as free as possible from albuminous constituents. 

 This is necessary in order that the enzyme employed may be obtained 

 on precipitation with alcohol without mixture with foreign albumi- 

 nous substances. As a culture medium for the bacillus pyocyaneus, 

 the following preparation is used : 



Distilled water, 1,000.0 



Asparagin, 5.0 



Sodium acetate, 5.0 



Dipotassium phosphate, 2.0 



Magnesium sulphate, 0.1 



Sodium chlorid, 2.0 



In order to prepare the nucleases in large quantities, from ten to 

 twelve liters of the above medium is divided in portions of one-half 

 liter each in liter flasks. These are inoculated and allowed to grow for 

 some weeks at 25°, and then for some weeks longer at from 30° to 37°. 

 After five or six weeks the cultures are shaken thoroughly at least 

 once in twenty-four hours, and when finally there remains only a 

 slight deposit of germ detritus, the supernatant fluid is drained off 

 12 



