294 SUMMARY OF CURRENT RESEARCHES RELATING TO 



which the plague bacillus is propagated upon the facility with which it 

 is ingested by human leucocytes. The work wa-; performed with 

 emulsions containing 2000 million organisms per c.cm. It was found 

 that an old laboratory strain of Bacillus pestis grown on heated horse, 

 rat, guinea-pig or human serum did not show any appreciable variation 

 in the phagocytic index with human leucocytes, when compared with the 

 original culture, but strains grown on fresh rat or horse serum showed a 

 high degree of resistance to phagocytosis. Plague bacilli taken direct 

 from an animal dying of plague show a marked reduction in capacity for 

 phagocytosis, which persists for a short time after cultivation on broth 

 agar outside the body. 



Morphology of the Plague Bacillus.* — S. Eowland discusses the 

 pleomorphism of the plague bacillus, illustrating his article with photo- 

 micrograms which show forms simulating micrococci, streptococci, 

 streptotricheEe, and moulds. Examination of broth cultures by trans- 

 mitted light, show a delicate halo around certain bacilli. Indian ink 

 preparations show that this halo is caused by the presence of a definite 

 envelope. This structure differs from the true capsule possessed by 

 certain bacteria in having no definite outer limit. Its consistence is 

 probably viscid ; by lucky manipulation with a needle, it can be drawn 

 out into a streaming appendage resembling the tail of a comet. The 

 well-known stickiness of plague cultures is probably due to this structure. 

 The presence of the envelope depends upon the nature of the culture 

 medium and the temperature of incubation. True capsules have been 

 observed by the author in bacilli at the site of inoculation in experi- 

 mentally infected rats and in bacilli grown upon a serum medium. 



The dark-ground illumination used to photograph some of the pre- 

 parations was obtained by using a central stop in an aplanatic condenser. 

 By this means a low-angled illuminating cone is produced, in contrast to 

 the excessively high angle of the rays emerging from a paraboloid. As 

 this eliminates light haze from small particles, it is a decided advantage. 

 Technical data referring to the photomicrograms are given. 



Intestinal Flora of Infants.t— E. Metchnikoff discusses the nature 

 of infantile diarrhoea, and shows that, the views of divers clinicians not- 

 withstanding, this is an infective disease due to a specific bacterial 

 invasion of the same order as cholera, typhoid, dysentery, and the like. 

 Experimental infantile diarrhoea in young rabbits produces a picture 

 closely resembling that of Asiatic cholera. The author considers that 

 the B. proteus in its many varieties is the primary causal factor in the 

 disease. 



D. M. Bertrand $ in w T ork upon infantile diarrhoea carried out in 

 London in 1912, found B. proteus in every one of fifty-five cases of 

 infantile diarrhoea. In the stools of 24 healthy children, he found this 

 organism twice only. Morgan's bacillus was not obtained from any 



* Journ. of Hygiene, xiii. (1914) Plague Suppl. No. 3, pp. 418-22. 

 t Ann. Inst. Pasteur, xxviii. (1914) pp. 91-120. 

 t Ann. Inst. Pasteur, xxviii. (1914) pp. 121-31. 



