46 VARIATIONS IN MORPHOLOGY [oh. iv 



guineapig bile ^o culture media, and they attribute the 

 modification to the action of the body fluids. Further, they 

 injected B. colt into the circulation in rabbits and found 

 subsequently enormous numbers of this diplococcic form of 

 the organism in the endothelial cells lining the hepatic vessels 

 and also in the cells of the liver, in the bile and in the kidneys. 

 These were detected within 30 to 60 minutes of the injection. 

 In some instances the modification was so marked that it was 

 not possible by passage or other means to obtain complete 

 reversion to type. In other cases after passage through 

 guineapigs reversion took place. The change was associated 

 with irregular staining, and with loss of motility, of fermenting 

 power and of power to produce indol. They found that 

 B. typJiosus underwent a similar modification under the same 

 circumstances. 



Jenner (1898) found that the diflerence in morphology 

 already mentioned in the case of B. coli isolated from water 

 disappeared after passage. 



Arkwright (1909) and other observers have described a 

 micrococcus closely resembling the meningococcus, found in 

 almost pure culture in the spinal fluid in many cases of 

 meningitis, which is characterised by a tendency to assume a 

 bacillary form. 



Ohlmacher (1902) inoculated a guineapig with a long 

 " granular " type of ^. diphtheriae but the organism recovered 

 later from the site of the inoculation proved to be of the 

 short " solid " type. The experiment was twice repeated with 

 the same result. In two other experiments with diflFerent 

 strains of B. diphtheriae the same observer found that during 

 "passage" through a guineapig the reverse change occurred, 

 a short "solid" type of organism being injected into the 

 animal and a long granular type recovered from the spleen 

 and liver after death. 



Mohler and Washburn (1906) claim that, by prolonged 

 growth in the living tissues of a suitable animal host, one type 

 of tubercle bacillus can be so modified with respect to its 

 morphological characters as to become indistinguishable from 

 another type. Baldwin (1910), however, grew a strain of the 



