268 BARBER AND TEAGUE. 



around the mask. This mask consists of a pad of absorbent 

 cotton held over the mouth and nose by a many-tailed gauze 

 bandage. 



(2) A hood of heavy Canton flannel cloth, covering the entire 

 head and tied in snugly at the neck, withstands much severer 

 tests than does the Mukden mask. It does not, however, offer 

 an absolute barrier to the passage of prodigiosus bacilli into 

 the mouth and nostrils of th© subject. This mask, with a 

 window in front, is not more inconvenient nor more uncomfort- 

 able than the Mukden mask. 



(3) It is shown that the inefficiency of the Mukden mask is 

 not due solely to the fact that the mask fails to conform to the 

 configuration of the face but that the bacteria may pass directly 

 through the mask ; for a piece of moist cotton placed in the center 

 of the mask was found after the test to contain prodigiosus 

 bacilli. 



(4) It is believed that, although masks hold back many bac- 

 teria that would otherwise pass into the mouth and nostrils, 

 nevertheless their use during the recent epidemic of pneumonic 

 plague in Manchuria lent a false sense of security which may 

 have led to the taking of unnecessary risks. We believe that 

 these experiments fully justify the conclusion that masks such 

 as were used in that epidemic do not offer an absolute protection 

 against pneumonic plague. 



