42 FREDERICK EBERSON 



on the basis of this alone would indicate a distinct property not common to 

 both organisms. In order to control the fermentation test, stained preparations 

 were made from both sets of tubes just before titrating, and the apparent 

 similarity of reaction was explained by the selective action of certain mediums 

 on the type of organism. Glycerol was found to inhibit the development of 

 cocci completely; dextrin had a similar action to a lesser degree. In all of 

 the remaining carbohydrates, the bacillary forms had been suppressed to a 

 remarkable extent. 



SEROLOGIC EXPERIMENTS 



Absorption of Agglutinins. The object of these experiments was to estab- 

 lish, if possible, by means of highly agglutinating serums, the relationship 

 of the bacillary diphtheroid to the diplococcus. Mellon, in his paper, concludes 

 that the streptococci are related to the diphtheroids and can be derived from 

 these. To establish such a claim it would be necessary to obtain pure strains 

 of each of these two types and show that they are mutually interchangeable. 

 This has not been shown by Mellon, and in the work reported here the results 



TABLE 2 

 ABSORPTION EXPERIMENTS WITH Coccus SERUM 



Serum C. Enzymicus Coccus 



1-20 1-40 1-80 1-160 1-320 1-500 1-1000 1-1500 1-2000 1-3000 1-4000 



C. enzymicus (coccus) + ++++ ++ ++ ++ + 

 C. enzymicus (bacillary) 



After absorption with C. enzymicus (bacillary) 



C. enzymicus (coccus) +4-++ ++ 4.4. 4.4. 4. -j. 

 C. enzymicus (bacillary) 



After absorption with C. enzymicus Strain 28 



C. enzymicus (coccus) ++++ ++ ++ ++ + 

 C, enzymicus (28 strain) 



do not substantiate his claim. It is evident that two organisms, derived one 

 from the other, should have similar, if not identical, antigenic properties. To 

 test the validity of such an assumption the most delicate method available is 

 that of agglutinin absorption, when the organisms in question are capable of 

 producing agglutinating serums. If the coccus type, obtained from a diph- 

 theroid culture, is truly derived from the bacillus, then a serum prepared with 

 one strain should agglutinate the other, and the absorption of agglutinins 

 should be demonstrable. With this idea in view, two serums were prepared 

 with the coccus strain and the bacillary strain, respectively. 



Healthy male rabbits were injected intravenously at 4-6 day intervals 

 with increasing doses of culture heated to 56 C. for 20 minutes. The dosage 

 progressed from }<) of an agar slant to a whole culture. Ten days after the 

 last injection the animals were exsanguinated and the serum, after heating to 

 S3 C. for 15 minutes, was stored at 4 C. until ready for use. The tests were 

 made with serum less than 6 days old. 



The technic of absorption was as follows : 24-hour old agar cultures of 

 the organisms were emulsified in a small volume of NaCl solution, heated 

 to 56 C. for 20 minutes, and centrifugated at high speed for a short time. 

 To the sediment so obtained the heterologous serum was added after deter- 

 mining by a preliminary agglutination test the potency of the homologous 

 serum. In order to ensure complete absorption the serums were diluted. The 



