BACILLARY DYSENTERY 397 



headache, fever, and anorexia occur, followed by great restlessness, 

 delirium, vomiting, often diarrhoea, and albuminuria. Frequently 

 broncho-pneumonia supervenes, and a fatal result has followed in about 

 a third of the cases observed. The organism has been isolated from the 

 blood of the heart. The psittacosis bacillus is evidently one of the 

 typhoid group, a fact which is further borne out by the observation that 

 it may be clumped by a typhoid serum. The clumping is, however, said 

 often to be incomplete, as the bacilli between the clumps may retain 

 their motility. It differs from the typhoid bacillus in its growth on 

 potatoes and in its pathogenicity. 



Danysz's Bacillus and Eat Viruses. Danysz isolated from an 

 epizootic in field mice an organism of this group, which he introduced 

 for the purpose of killing rats by originating in them through feeding a 

 similar epizootic, and several viruses of this kind are in commercial use 

 for this purpose. These have been investigated by Bainbridge, who, 

 however, finds that they owe any efficiency they possess to the bacillus 

 ./Ertryck and the bacillus enteritidis of Gaertner. The efficacy of such 

 agents varies, and the mortality in artificially originated epizootics is 

 from 20 to 50 per cent. Sometimes, apparently under natural conditions, 

 rats develop an immunity to those viruses, and it is doubtful whether 

 they are entirely innocuous to other animals which may partake of the 

 food containing them. 



BACILLARY DYSENTERY. 



Dysentery has for long been recognised as including a number 

 of different pathological conditions, and within more recent times 

 amoebic and non-amoebic forms have been distinguished. Of the 

 latter, bacteria have been believed to be the causal agents, and 

 an organism described by Shiga in 1898 has almost certainly 

 been established as the cause of a large proportion of cases. 

 Shiga's observations were made in Japan, and confirmatory 

 results have been obtained by Kruse in Germany, by Flexner and 

 by Strong and Harvie in the Philippine Islands, and by Vedder 

 and Duval in the United States. It is now further recognised 

 that the epidemics of dysentery which from time to time occur 

 in lunatic asylums are usually due to bacilli of this type, and in 

 America the organism has been demonstrated in summer 

 diarrhoea in children. The evidence for the relationship of the 

 organism to the disease consists chiefly in its apparently constant 

 presence in the dejecta in this form of dysentery, and in the 

 agglutination of the organism by the serum of patients suffering 

 from the disease, but confirmatory evidence has also come from 

 animal experimentation and from the success following a use 

 of antisera prepared by means of the bacilli. From different 

 epidemics a great many different strains of the dysentery bacillus 

 have been obtained, but these possess common characters and 

 are closely related to one another. The various strains resolve 



