EFFICACY OF VARIOUS MASKS. 



265 



the air at the time of the exposure. Furthermore, the number 

 of living" bacilli in the air in the cold room remains practically 

 constant during the ten minutes of the test, while, as we have 

 seen, in the warm stable there is a rapid decrease. This ex- 

 periment shows again the superiority of our Broquet mask over 

 the Mukden mask. It also proves that prodigiosus bacilli may 

 pass directly through the cotton pad of the Mukden mask, for 

 a piece of moist cotton placed near the center of the pad contained 

 prodigiosus bacilli after the test. The mask of wet gauze also 

 failed to hold back all the bacilli and is hence inferior to our 

 Broquet mask. The experiment does not afford any evidence 

 as to the relative efficiency of the Mukden mask and the mask 

 of moist gauze. 



PROTOCOL NO. 5. 



March 1, 1912. The mouth of one of us was rinsed with sterile salt 

 solution and then about 10 cubic centimeters of saliva were collected in a 

 sterile test tube. One slant of a fresh prodigiosus culture was suspended 

 in this saliva. The resulting suspension was thoroughly shaken and then 

 taken a little at a time into the mouth and made into a spray by being 

 blown between the lips. The spraying was done in a cold storage room 

 at 9°C. The room was then kept closed for one hour, when the three masked 

 subjects were quickly taken in and the door closed behind them. They 

 remained inside ten minutes, each subject holding during that time an 

 open Petri dish of solidified agar. 



The masks were removed and cultures made as in the preceding 

 experiment. 



Number of living prodigiosus bacilli in the air. 



Plate held by subject No. 1 

 Plate held by subject No. 2 

 Plate held by subject No. 3 



Number of 



prodigiosus 



colonies. 



2,340 

 2,405 

 3,120 



Subject No. 1. Mukden mask. 



Saliva taken before exposure 



f Plate No. 1: 



[Plate No. 2: 



Cotton from nostrils before exposure Plate No. 1 : 



r< A.4. r i. -1 ri. f Plate No. 1 : 



Cotton from nostrils after exposure {-r^, . 



IPlate No. 2: 



Cotton before mouth after exposure i^^ ^ >t r. 



(Plate No. 2: 



Cotton within the mask after exposure 

 Saliva taken after exposure 



f Plate No. 1: 



iPlate No. 2: 

 fPlate No. 1: 

 jpiate No. 2: 



Prodigiosus 

 Prodigiosus 

 Prodigiosus 

 Prodigiosus 

 Prodigiosus 

 Prodigiosus 

 Prodigiosus 

 Prodigiosus 

 Prodigiosus 

 Prodigiosus 

 Prodigiosus 



absent. 



absent. 



absent. 



present. 



present. 



present. 



present. 



present. 



present. 



absent. 



absent. 



