134 SUPPOSED INSTANCES [CH. ix 



B. The experiments ofMiihlens, Dahm and Filrst. 



These writers (1909) have recorded experiments which 

 suggest a similar transmutation. They fed a large number of 

 mice on meat which was thought to have been infected 

 although a preliminary bacteriological examination proved 

 negative. Over 50 per cent, of the mice died. 



A bacteriological examination of the faeces of 56 mice was 

 made. In 20 cases none of the paratyphoid group of bacilli 

 were detected. Aertryck's bacillus was found to be present in 

 24 and Gaertner's bacillus in 13 cases. 



These results suggest that one type may have arisen from 

 the other within the animal body. 



As in the experiments already discussed, two possibilities 

 have first to be excluded namely, the possibility of con- 

 tamination (a) in the original strain and (b) in the bodies of 

 the mice used for the experiment. 



(a) All that can be said by way of excluding the first of 

 these alternatives is that the simultaneous presence of both 

 the Aertryck and the Gaertner type of organism in infected 

 meat is contrary to experience and was thought by other 

 writers (Zwich and Weichel, 1910) to be highly improbable 

 in this instance. 



(b) With regard to the second alternative, no preliminary 

 bacteriological examination of the mice used in the experi- 

 ment was made. The faeces of 40 control mice were examined 

 and B. Gaertner was discovered in one case only. Zwich and 

 Weichel (1910), on the other hand, found that out of 177 

 healthy mice 28 gave B. Aertryck in the faeces. 



The bacteriological examination of the 40 control mice 

 with a negative result in 39 cases is, again, open to the 

 criticism that paratyphoid organisms might have been 

 actually present at the time but in such small numbers that 

 they escaped detection. Any such organisms present, in 

 equally small numbers, in the other mice would find a nidus 

 for their growth in the unhealthy and inflamed condition of 

 the intestine which would result from feeding the mice on 

 infected meat, while the disturbed functions of the bowel, by 



