PHYLACOGENS 499 



effects of a single species of organism (the specific infection) but to 

 tiie influence of other organisms whose pathogenic role is not insignifi- 

 cant, but which must be reckoned with, in any successful scheme of 

 therapeutics. The preparation of phylacogens is as follows : 



" They are sterile, aqueous solutions of metabolic substances or 

 derivatives generated by bacteria grown in artificial media. The bac- 

 teria first killed, are removed by filtration through porcelain. To, 

 determine sterility, the phylacogens are subjected to careful cultural 

 tests. 



" The phylacogens are made from a large variety of pathogenic 

 bacteria, such as the several staphylococci, Streptococcus pyogenes. 

 Bacillus pyocyaneous, Diplococcus pneumonias. Bacillus typhosus. 

 Bacillus coli communis, Streptococcus rheumaticus, Streptococcus 

 erysipelatis, etc. This basic Phylacogen is a ' polyvalent ' prepa- 

 ration or Polyphylacogen, since the organisms are not from one strain 

 only of a given species, but from cultures made at frequent intervals 

 and from a, variety of sources. The various organisms are present in 

 the material before filtration and dilution in approximately equal pro- 

 portions. The cultures are incubated at 37° C. for 72 hours or 

 longer, after which a preservative consisting of 0.5 per cent, of phenol 

 is added to the fiuid, which is then filtered through porcelain. The 

 basic phylacogen, made in this manner, is used in the preparation of 

 the several specific phylacogens. It has been named Mixed Infection 

 Phylacogen. 



" Each specific - phylacogen is prepared as follows : The basic 

 material (Mixed Infection Phylacogen) is modified by the addition 

 of an equal amount of the filtrate obtained by growing and treating 

 the organism considered to be predominant in the pathological condi- 

 tion to be treated; for instance, in the preparation of typhoid phy- 

 lacogen, the Bacillus typhosus is grown and treated like the several 

 organisms entering into the preparation of the basic Mixed Infection 

 Phylacogen. The filtrate obtained from the preparation of the 

 typhoid organism alone is added in equal amount to the Mixed Infec- 

 tion Phylacogen, and the resulting product given the specific name 

 " Typhoid Phylacogen." A similar method is employed in the manu- 

 facture of the other specific phylacogens, such as pneumonia, gonor- 

 rhea, tuberculosis, erysipelas, etc., etc." 



In veterinary medicine, two phylacogens are now used. They are 

 mixed infection phylacogen and pneumonia phylacogen prepared 

 from Diplococcus pneumonia. 



Use. These agents on account of their " polyvalent " character 

 should be used with great caution by the veterinarian. As was 

 pointed out in the use of Bacterins, there is a tendency to use a bio- 

 logical agent whether it has any definite relation to the disease or not. 

 " Shot-gun prescription " biologies are not to be recommended any 

 more than " shot-gun prescriptions " using drugs. 



