STRAINS OF PATHOGENIC BACTERIA 125 



in 1888 and 1889 the type No. 1 was never isolated, but the other 

 varieties were present, and the cases were severe. 



Foa 1 has shown that by inoculation variation may be 

 induced in the diplococcus. If from a rabbit that has died of 

 inoculation pneumonia two rabbits be inoculated, one from 

 the fresh fibrinous pneumonic exudate, the other from the 

 cerebro-spinal fluid, it is found that the disease differs in the 

 two. The former shows inflammatory oedema of the skin, the 

 latter none. So, too, if the diplococcus be grown for twenty- 

 four hours anaerobically the latter type is produced and its 

 properties persist, although the original virulence and characters 

 may be restored by simultaneous inoculation of this form along 

 with the Staphylococcus pyogenes aureus and the proteus vul- 

 garis. These studies of Foa find their counterpart in Banti's 

 researches into acute primary meningitis. 2 From two cases of 

 this disease Banti isolated a diplococcus not to be distinguished 

 from that of Talamon-Frankel, except that it rapidly lost its 

 virulence both inside and outside the body, so that when the 

 meningeal exudation was inoculated into a rabbit, and from 

 this a further series of passages was made, the sixth rabbit had 

 a mild non-fatal disease. 



In the case of typhoid, Babes 3 has made a long series of 

 observations, and though he handles the subject with what for 

 him is extreme caution, it is difficult to arrive at any other con- 

 clusion than that the facts he represents can only be satisfactorily 

 accounted for on the assumption that, granting there be a specific 

 micro-organism for typhoid, and granting his results to be reliable, 

 this micro-organism is capable of modifications so definite that 

 many races are developed. Babes made numerous cultures 

 from twelve typhoid corpses, and while in nearly every case he 

 found the typical form, in every case he discovered also varieties. 

 In all he describes eighteen of these, all presenting some slight 

 differences. These were sufficiently permanent to permit him 

 to declare that he never saw one revert to the original form 

 (as determined by an original culture from Berlin), although in 

 many there was a tendency towards the loss of characteristics. 



1 Foa, International Medical Congress, Berlin, 1890 (Section of General 

 Pathology). 



2 Banti, Lo Sperimentale, xliii., 1889, p. 138. 



3 V. Babes, Zeitschrift f. Hygiene, ix., 1890, p. 323. 



