General Classification 56 



(Can the Various Strains of Pfeiffer's Bacillus be divided into Natural 

 Groups? Are the Strains of Pfeiffer's Bacillus found in Healthy Persons 

 and in other Diseases than Influenza Different from those found in 

 Influenza?). 



Pfeiffer's Bacillus and Influenza 58 



(Experimental Inlluenza (58) — Pathogenic Characteristics for Man and 

 Animals (58) — Pfeiffer's View (59) — Attempt at a General Review of 

 the Conditions of Development and Method of Spreading of Pfeiffer's 

 Bacillus (59) — Possible Objections to the View set forth. The Problem 

 is still unsolved with regard to several Points (63)). 



THE AUTHOR'S INVESTIGATIONS. 



II. Investigations upon the Occurrence of Pfeiffer's Bacillus. 



Introduction 67 



The Originally Employed Signs and the Technique in Connection with 

 them 68 



1 . Occurrence in Influenza 72 



(a. Summer Epidemic 1918 (72) — b. Autumn and Winter Epidemic 

 1918—19 (73) — c. Epidemic in 1920 (78) — d. Epidemic in 1922 (78) 



— General Remarks upon the Investigations in Influenza (79)). 



2. Occurrence in Whooping-cough 81 



3. — Measles 81 



4. Tuberculosis 82 



5. Meningitis 83 



6. Healthy Persons . 84 



(General Considerations (84) — a. Newly-enlisted Soldiers (85) — b. 

 Other Healthy Persons (88) — Discussion (91)). 



/ 7. Occurrence in Animals 96 



Review of all the Strains 96 



III. Analysis of the Bacterial Group »Pfeiffer's Bacillus«. 



Introductory Remarks 98 



On the Haemoglobinophilic Character of Pfeiffer's Bacillus 101 



(Some Main Points from the Literature (101) — Auihor's Investigations: 

 Conditions on Ordinary Agar and Ascitic Agar in Pure Culture and in 

 the Presence of other Bacteria (103) — Dependence of the Medium on 

 the Haemoglobin Concentration (110) — Experiments on Weaning from 

 Haemoglobin (113) — Discussion (113)). 



The Symbiosis Phenomenon 115 



(Some Main Points from the Literature (115) — Author's Investigations: 

 Technique Employed (120) — Discussion of Technique (121) — Sym- 

 biosis Phenomenon as ^Distance Effect" (125) — Typical and Atypical 



