260 BARBER AND TEAGUE. 



The cotton was wet in order to afford conditions for growth to any B. 

 prodigiosus which might otherwise have remained in the dry center of 

 the cotton. (In a few cases the wet cotton mass alone, after twenty-four 

 hours, showed the red color indicative of the growth of B. prodigiosus.) 

 All plates were left in the dark at room temperature (25° to 30°C.)> 

 protected by glass jars. 



The result of all the cultures, read two days later, was as follows: 



Boy No. 1. Mukden mask. 



a T +1 ^. f fPlate No. 1 



Saliva taken before exposure ipi + N 9 



Cotton from nostrils before exposure ] pi - -vr ' o 



Cotton from nostrils after exposure ]pi . -mo 



Cotton before mouth after exposure ]pi j. -vr " o 



Cotton within the mask after exposure 



JPlate No. 1 

 [Plate No. 2 



Prodigiosus absent. 

 Prodigiosus absent. 

 Prodigiosus absent. 

 Prodigiosus absent. 

 Prodigiosus present. 

 Prodigiosus present. 

 Prodigiosus present. 

 Prodigiosus present. 

 Prodigiosus present. 

 Prodigiosus present. 



Boy No. 2. Canton flannel Broquet mask. 



„ ,. ^ I , „ fPlate No. 1: Prodigiosus absent. 



Saliva taken before exposure i-r>i . t^t r, -n j- • i. 



[Plate No. 2: Prodigiosus absent. 



„ , . „ . ■■, y J- f Plate No. 1: Prodigiosus absent. 



Cotton from nostrils before exposure -^t-,, ^^ ^.t - t-, ^■ ■ ■, 



[ Plate No. 1 : Prodigiosus absent. 



„ , , , . .-, nj_ fPlate No. 1 : Prodigiosus present. 



Cotton before mouth after exposure -^t^, . ■.,. r. -i-. j- • 



1 Plate No. 2: Prodigiosus present. 



Cotton from nostrils after exposure 



JPlate No. 1: Prodigiosus present. 

 [Plate No. 2: Prodigiosus present. 



A plate exposed to the air of the laboratory room, while the above 

 plates were being prepared, showed no red colonies. 



DISCUSSION OP PROTOCOL NO. 1. 



This experiment shows that neither the Mukden mask nor 

 the heavy Canton flannel Broquet mask is able to hold back 

 completely prodigiosus bacilli when they are sprayed in large 

 numbers continuously for a period of three minutes about the 

 heads of the subjects. As this Broquet mask is the most effi- 

 cient of all the masks with which we have experimented, it 

 follows that none of our masks can withstand this test. The 

 fact that the moist cotton from the center of the Mukden mask 

 contained many prodigiosus bacilli shows that some of the pro- 

 digiosus bacilli passed directly through the mask; or, in other 

 words, that the inefficiency of this mask is not due solely to 

 the fact that the bacilli pass around the edges of the cotton pad 

 or through the free spaces at the sides of the nose which were, 



