132 SUPPOSED INSTANCES [CH. ix 



calf s blood on the same day. It was found to be agglutinated 

 by the animal's blood serum in dilutions of 1 in 50 — 60 

 although, again, serum which had been- taken from the calf 

 before the experiments began failed to agglutinate it. (A 

 calf serum, immunised against a Gaertner strain from cattle, 

 was on the same day injected intravenously but only made 

 the calf more ill.) A broth culture of this organism, Pgst I, 

 was injected into the same animal on August 7th and again 

 on August 10th, giving rise only to a slight febrile reaction 

 on each occasion. 



Experiment II, On August 25th, the strain already 

 mentioned (Pgst I) as having been isolated from the first 

 calf 8 blood was suspended in normal saline and sprayed into 

 the nose of another calf — without apparent effect. On August 

 28th a similar suspension was injected into the animal's 

 mouth with the result that the calf became ill. An organism 

 (Pgst II) was isolated from the calf s blood. On September 

 4th a saline suspension of this organism was injected intra- 

 venously into the same calf, which died a few hours later. From 

 the blood, intestines, muscles and bone marrow was obtained 

 an organism Pgst III. The " Schluss-serum " was found to 

 agglutinate the original Flugge type and also the strains 

 Pgst I, II, and III— in dilutions of 1 in 3000—4500. 



The great interest of the experiments lies in the obser- 

 vation that these later strains isolated from the blood of the 

 calf were found to correspond in their agglutination reactions, 

 not with the original Flugge type but with the Gaertner type 

 of bacillus — a conclusion confirmed by absorption tests, 

 Schmitt maintained, therefore, that passage through the calf 

 modified the agglutination properties of the human para- 

 typhoid bacillus ("Flugge") so that it came to resemble the 

 calf paratyphoid bacillus (" Gaertner "). 



Two passible fallacies at once suggest themselves. The 

 type of organism which made its appearance later in the 

 experiment might have been present as a contamination either 

 (a) in the original strain or (6) in the bodies of the animals 

 inoculated. 



(a) As regards the first alternative, it is conceivable that 



