BACILLUS COLI COMMUNIS 183 



pathogenic power. By passage from animal to animal, however, 

 the virulence may be much increased, andparipassu the effects of 

 inoculation are correspondingly varied. Marmorek, for example, 

 found that the virulence of a streptococcus can be enormously 

 increased by growing it alternately (a) in a mixture of human 

 blood serum and bouillon (vide page 41), and (6) in the body of 

 a rabbit ; ultimately, after several passages it possesses a super- 

 virulent character, so that even an extremely minute dose intro- 

 duced into the tissues of a rabbit produces rapid septicaemia, with 

 death in a few hours. It has been proved by Marmorek's experi- 

 ments, and those of others, that the same species of streptococcus 

 may produce at one time merely a passing local redness, at 

 another a local suppuration, at another a spreading erysi- 

 pelatous condition, or again a general septicaemic infection, 

 according as its virulence is artificially increased. Such experi- 

 ments are of extreme importance as explaining to some extent the 

 great diversity of lesions in the human subject with which strep- 

 tococci are associated. 



Bacillus Coli Communis. The virulence of this organism also 

 varies much and can be increased by passage from animal to 

 animal. Injection into the serous cavities of rabbits produces a 

 fibrinous inflammation which becomes purulent if the animal 

 lives sufficiently long. If, however, the virulence of the organism 

 be of a high order, death takes place before suppuration is 

 established, and there is a septica3mic condition, the organisms 

 occurring in large numbers in the blood. Intravenous injection 

 of a few drops of a virulent bouillon culture usually produces a 

 rapid septica3mia with scattered hemorrhages in various organs. 



Other Effects. It has been found by independent observers that in 

 cases where rabbits recover after intravenous injection of bacillus coli 

 communis, a certain proportion suffer from paralysis and sometimes from 

 atrophy of muscles, especially of the posterior limbs, these symptoms 

 being due to lesions of the cells in the anterior cornua of the spinal cord. 

 Somewhat similar results have been obtained by others after inoculations 

 with staphylococci and streptococci, a certain proportion only of the 

 animals showing paralytic symptoms and corresponding changes in the 

 spinal cord. The lesions are believed to be due chiefly to the action of 

 the products of the organisms on the highly organised nervous elements. 

 Much further research requires to be done before the importance of these 

 results can be properly estimated, but it is not improbable that they 

 will throw light on the causation of nervous lesions which occur in the 

 human subject, and the etiology of which at present is quite obscure. 

 Some observers, chiefly of the French school, consider that paralysis 

 associated with cystitis, in which the bacillus coli communis is often 

 present, may have such a causation, and that paralytic conditions 

 following acute infective fevers may be produced by the products of 

 pyogenic cocci, which frequently occur in these conditions. 



