TWELFTH ANNUAL REPORT 47 



in the transmission of bubonic plague has received further 

 confirmation from the study of an outbreak of plague among 

 guinea pigs in the animal house, in which transmission by rat 

 fleas was demonstrated and in which all other methods of trans- 

 mission were excluded. The finding of a naturally infected 

 plague cat confirms the belief that these animals might be a 

 source of infection to man in plague epidemics. An extended 

 pathological study of the lesion of bubonic plague, as found 

 in the human cases during this outbreak, is now in progress 

 by the pathologist of this laboratory. 



Cholera. — A new and quicker procedure in the isolation and 

 identification of the vibrio of Asiatic cholera has been devised, 

 but owing to the absence of cases of this disease in the Phil- 

 ippines the work is unfinished. The method depends on the 

 separation of cholera vibrios from other bacteria by the use 

 of agglutinating serums in pipettes and by making use of the 

 positive chemiotaxis of cholera vibrios in the presence of certain 

 substances. The importance of the earliest possible diagnosis 

 of cholera in preventing the spread of the disease is recognized, 

 and this new method promises to be of material aid to this 

 end. 



Bacillary dysentery. — A study has been made of morphological 

 and biological variations in strains of Bacillus dysenterise, isolated 

 by the single-cell method. Several strains have been isolated 

 which showed morphological variations and differences in their 

 capacity to ferment carbohydrates, and certain of these varieties 

 have been found to be constant. This work has a practical 

 bearing on the diagnosis of dysentery. An investigation of the 

 bacteriology of infantile diarrhoeas is now in progress. 



Infection studies with the bacteria of cholera, dysentery, and 

 plague and with Bacillus pyocyaneus and Aspergillus injected 

 into the cells of the mold Achlya have been carried on. They 

 included principally a study of the permeability of the walls 

 of the plant for agglutinins and acids with the treatment of 

 infections by these substances. 



Tubercidosis. — A study of tuberculosis infection in animals 

 has demonstrated the greater resistance of guinea pigs to infec- 

 tion with bacilli from human sources under conditions obtain- 

 ing here than in temperate climates, and an attempt to immunize 

 guinea pigs with virulent cultures of tuberculosis has resulted 

 negatively. Also, a study of the occurrence of tuberculosis 

 associated with leprosy and the investigation of a strain of 

 tubercle bacilli from a leprous patient which has produced a 



