VII! n. '■' Schobl: Plague in Manila in 1912 415 



From the preceding observations the following conclusions are 

 drawn : 



1. The importance of blood cultures as a diagnostic means is 

 evident from the fact that positive blood culture was obtained 

 in practically every case that was examined in the febrile stage 

 of the disease, even when buboes or signs of pulmonary involve- 

 ment had not been detected clinically. 



2. It is also evident that Bacillus pestis may be found in the 

 circulating blood of the patients even in cases which subsequently 

 recover. 



3. The period of time during which Bacillus pestis circulates 

 in the blood is evidently short and irregular. 



4. Mixed infection may be encountered in plague septicaemia 

 (Streptococcus, Pneumococcus) . 



5. The agglutination test is of no value for the diagnosis of 

 plague, as it was found positive only in convalescents. 



6. Phagocytosis of plague bacilli in the bubo was noticed only 

 in patients who recovered after being vigorously treated with 

 curative serum. 



7. The presence of numerous plague bacilli in comparatively 

 insignificant skin lesions during the life of the patient points 

 to the possibility of direct transmission, while the fact that a 

 patient without any apparent bubo, who is not so sick as to 

 be detained from his daily occupation, may expectorate large 

 numbers of plague bacilli, are facts of great importance with 

 regard to the communication of the disease. It is obvious that 

 the last-mentioned condition might, and very likely does, give 

 rise to an epidemic of pneumonic plague if the atmospheric 

 and sanitary conditions are favorable. 



II. OBSERVATIONS ON THE TRANSMISSION OF PLAGUE BY 

 BLOODSUCKING INSECTS 



Judging from the data which have been collected from the 

 literature* on the transmission of plague (Table III), Simond 

 seems to have been the first to call attention to the important 

 part which bloodsucking insects, particularly fleas, play in the 



'Centralbl. f. Backt., 1 Abt. (1897), 22, 87, 437. 

 Report of Indian Plague Commission (1898-99). 

 Zeitschr. f. Hyg. %i. Infectionskrankh. (1901), 36, 89. 

 Kolle und Wassermann. Handbuch der pathogenen Mikroorganismen 

 (1903), 2, 538. 



Zeitschr. f. Hyg. u. Infectionskrankh. (1905), 51, 268. 

 Joum. Hyg., Cambridge (1907-10), plague numbers. 

 Ibid. (1908), 8, 162, 260. 



