[Vor. 1 
70 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
The reactions of the cocci isolated from the air in the first 
filter showed that there was one salivary coceus form present. 
The remaining three gave negative reactions on the three differ- 
ential media. It should be noted that out of the 15 cc. of solu- 
tion from the first filter, only 4 cc. were plated. Eight organ- 
isms were present in the quantity examined, making a total of 30 
in the entire solution. One characteristic salivary coccus form 
developed in the portion examined, making, according to the 
law of averages, a total of 4 in the entire solution. The total 
volume of air examined being 7,800 cc., the frequency of occur- 
rence of the salivary coccus is 1 in 1,950. According to table 
vi, the sanitary quality of the air of the room was ‘probably 
unsafe" at the particular time at which the sample was taken. 
EXPERIMENTS 3, 5. 6, 8, 10 
These experiments were carried out in a local street car. 
The same car line was chosen for all of the experiments in order 
to eliminate as many variables as possible, such as construction 
of ear, capacity, rate of locomotion, etc. Тһе car was of the 
ordinary ‘‘pay-as-you-enter” type now in use in St. Louis. 
It had a seating capacity of about 44 people, and could accom- 
modate approximately 40 more standing indoors. The air 
space in the car in question was about 2,500 cubic feet, or ap- 
proximately 30 cubic feet for each passenger when the car was 
filled to its capacity. 
As the samples were taken at a time when the outside tem- 
perature would not permit the windows to be open, the question - 
of ventilation was carefully studied. Ав is usually the case, 
the transoms were tightly closed, and only when the front and 
rear doors of the car were open at the same time was there an 
opportunity for a complete renewal of the air. This never 
happens when the car is in motion, and there is probably never 
a complete renewal of air unless a strong wind is blowing, thus 
causing a draught when the car is at a standstill, with both doors 
open. This particular car was provided with four vents in the 
roof which could be opened or closed at will. In several of the 
experiments some of the vents were open; in others, all were 
closed. 
The degree of pollution of the atmosphere in such a car de- 
