354 BACILLARY DYSENTERY. 



examination of chronic cases of the disease post mortem, it is 

 usually difficult to isolate the bacillus on account of the large 

 number of bacillus coli and other bacteria present ; in such 

 cases it is advisable to scrape the ulcerated mucosa with a 

 sterile knife and from the scrapings make numerous dilutions 

 in agar. Lactose litmus agar may be found helpful in differen- 

 tiating colon colonies from those of bacillus dysenteriae inasmuch 

 as the former colonies appear red through the production of 

 lactic acid, whilst the latter, not forming acid, remain blue. 



Bacillus Dysenteriae (Ogata). Ogata obtained this bacillus in an ex- 

 tensive epidemic in Japan in which no amoebae were present. He found in 

 sections of the affected tissues enormous numbers of small bacilli of about the 

 same thickness as the tubercle bacillus, but very much shorter. These bacilli 

 were sometimes found in a practically pure condition. They were actively 

 motile and could be stained by Gram's method. He also obtained pure 

 cultures 'from various cases and tested their pathogenic effects. They grew 

 well on gelatin at the ordinary temperature, producing liquefaction, the growth 

 somewhat resembling that of the cholera spirillum. By injection into cats 

 and guinea-pigs, as well as by feeding them, this organism was found to have 

 distinct pathogenic effects ; these were chiefly confined to the large intestine, 

 haemorrhagic inflammation and ulceration being produced. It still remains to 

 be determined whether this organism has a causal relationship to one variety 

 of dysentery. 



BACILLUS ENTERITIDIS SPOROGENES. 



This organism was first isolated by Klein from the evacuations in an out- 

 break of diarrhoea following the ingestion of milk which contained the 

 microbe, and it was subsequently found by him in certain cases of infantile 

 diarrhoea and of summer diarrhoea, in certain instances in milk, and as a 

 constant inhabitant of sewage (see Chapter IV.). In films made from the 

 stools in diarrhoea cases where it is present it can be microscopically recog- 

 nised as a bacillus i.6/x to 4.8/z in length and .8/x in breadth, staining by 

 ordinary stains and retaining the dye in Gram's method. It often contains a 

 spore near one of the ends, or sometimes nearer the centre. It is slightly 

 motile, and in cultures can be shown to possess a small number of terminal 

 flagella. It grows well under anaerobic conditions on ordinary media, espe- 

 cially on those containing reducing agents. On agar the colonies are circular, 

 grey, and translucent.- and under a low power are seen to have a granular 

 appearance. On this medium spore formation does not occur, but is easily 

 obtained if the organism is grown on solidified blood serum, which, further, is 

 liquefied during growth. On gelatin plates liquefaction commences after 

 twenty-four hours at 20 C. The bacillus grows well on 2 per cent dextrose 

 gelatin, and besides the liquefaction there is here great gas evolution. Spore 

 formation can be seen to take place in this medium, but the degree seems to 

 be in inverse ratio to the amount of gas formation. Very typical is the growth 



