[Vor. 1 
66 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
TABLE VI 
TEST FOR CHARACTERISTIC SALIVARY COCCI IN AIR 
Safe О О O о + 
Reasonably safe О O O + + 
Questionable O O + + + 
Probably unsafe O + 4 + 4- 
Unsafe 4 + + + + 
+ indicates positive reaction in the three differential media adopted. 
APPARATUS AND TECHNIQUE 
As it was the intention to collect samples of air in places other 
than the laboratory, a portable apparatus was necessary. As 
devised, it consists essentially of a sand filter, a support for same 
with an attachment for alternately opening and closing the 
exhaust and suction, and a bulb, having a capacity of 16 oz., 
with the required amount of rubber tubing. (See plate 2.) 
The sand filter is of the standard type. It consists of a glass 
tube 100 mm. long and 10 mm. in diameter, fitted with a one- 
hole rubber stopper, through which passes a piece of 6 mm. glass 
tubing. This stopper, with its tubing, forms the support for а 
cireular disc of bolting cloth with a 10 mm. layer of very fine 
clean quartz sand that passes through a 100, and is retained on à 
140 mesh sieve. 
The support consists of a rectangular piece of wood 12 
x 1 x 3 inches, fitted with a double pinch cock arrangement. 
Clamps for holding the filter in position are also provided. Тһе 
rubber bulb is connected to the apparatus in such а manner that 
when pressure is applied to the former and the pinch cock opened, 
the air contained in the bulb is expelled through the exhaust 
without disturbing the sand in the filter in any way. This 
operation occupies but a few seconds of time. Upon releasing 
the pinch cock, and immediately thereafter the bulb, the air is 
drawn through the sand. 
