ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 295 



case. Other organisms, associated by sundry workers with the disease, 

 were but rarely encountered. 



H. Berthelot,* in his experimental observations upon the pathogenic 

 properties of certain bacterial associations, regards the B. proteas from 

 another aspect. In experiments on rats, he finds that this organism 

 alone produces no ill-effects, but, if combined with B. aminophilus intesti- 

 nalis — a close ally of B. lactis aerogenes — will give rise to a rapidly fatal 

 diarrhoea. The latter organism alone is harmless. He discusses in 

 detail the pathogenic properties of B. proteas and other bacteria growing 

 in symbiosis, and concludes that various types of colitis, infantile diarrhoea, 

 and allied conditions are due to the presence of B. proteus associated 

 with one or more types of acidaminolytic organism. 



Mechanism of the Transmission of Plague by Fleas. f—C. J. 

 Martin and A. W. Bacot have carried out researches which throw light 

 upon the means by which the flea may transmit plague from an infected 

 to a healthy host. When a flea is fed upon an animal suffering from 

 septicgemic plague, bacilli enter the alimentary canal, passing through 

 the proventiculus into the stomach, and grow freely in this position. 

 Plague bacilli from the flea's stomach were found to possess a diminished 

 degree of infectivity, and were readily ingested by human leucocytes. 

 This effect may be due to the action of the digestive juices of the flea. 

 It would appear from this that organisms in the flea droppings may 

 show little virulence. In some fleas it was observed that plague bacilli 

 grew vigorously in the proventiculus, forming a solid plug of culture, 

 obstructing the passage into the stomach. A flea so affected sucks with 

 increased vigour, when applied to a host, and the proventiculus becomes 

 distended with fresh blood. At the end of the act of sucking, the 

 proventriculus contracts upon the mixture of blood and bacilli, and in- 

 fective material is regurgitated upon the puncture wound of the animal 

 attacked. It is probable that these obstructed fleas are the cause of 

 most cases of natural infection. Further, fleas may recover from this 

 condition when the contents of the crops autolyse, but on the other 

 hand many individuals become desiccated in the hot weather. This may 

 account for the interruption of plague epidemics in India when the 

 temperature rises. 



Calymmato-bacterium granulomatis.J — H. De B. Aragao and 

 Gr. Vianna report that they have isolated from a venereal disease endemic 

 in Brazil, and characterized by the presence of granulomatous tissue, a 

 bacterium, the most marked feature of which is a large well-marked 

 capsule. The bacterium is somewhat polymorphic, both coccous and 

 bacillous forms existing. The organism, which is Gram-negative, is 

 best stained by Giemsa. In the tissues it is found both as an intra- and 

 extracellular parasite ; in the former the capsule is often absent, but is 

 well marked in the extracellular tissue. Successful cultivations were 



* Ann. Inst. Pasteur, xxviiii. (1914) pp. 131-48. 



t Journ. of Hygiene, xiii. (1914) Plague Suppl. No. 3, pp. 423-9. 



$ Memorias do Institute Oswaldo, Cruz, v. (1913) pp. 211-38 (6 pis.). 



