[Vor. 1 
04 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
further indicate that the production of acid in lactose and вас- 
charose broths, and a similar production, together with clot, in 
milk, are characteristic reactions of the salivary cocci. 
CONCLUSIONS 
From the results of the preceding experiments it appears 
that а method applicable for the detection of the organisms 
characteristic of human saliva has been developed. 
It must be acknowledged that the number of organisms 
examined is comparatively small, especially where those of 
the air and the skin are concerned. Ап absolute test of the 
validity of the adopted mode of identification would necessitate 
the examination of many hundreds of strains of cocci from 
numerous sources. 
Nevertheless, the characteristie reactions of the salivary 
cocci examined seem to be sufficiently definite to warrant the 
assumption that the most characteristic salivary organism is 
a coccus form which produces acid in lactose and saccharose 
broths, and acid and clot in milk. 
Тнв RELATION OF THE Most CHARACTERISTIC SALIVARY 
ORGANISM TO THE POLLUTION OF AIR 
Having identified the most characteristic salivary organism, 
the next problem is to isolate it from the air. Its frequency 
of occurrence must also be determined, as this often serves as 
an index to the degree of pollution. The isolation of the organ- 
ism and the determination of its frequency of occurrence can be 
accomplished simultaneously. 
Then come the problems (1) of devising an air-collecting 
apparatus suitable for all occasions, and (2) of determining the 
quantity of air to be examined and the terms by which the 
sanitary quality of the air shall be expressed. 
In searching for a means of expressing the sanitary quality of 
air, let us consider the manner in which this is accomplished 
in drinking water. Authorities differ markedly on this subject. 
Shall a water be considered safe or unsafe for drinking purposes 
if B. coli is present in a 100 cc. sample, or shall its presence or 
absence in 10 cc. or 1 се. samples be taken as the basis for the 
