PROTOZOAN FAUNA OF HAY INFUSIONS PAIL 
It is believed that in this series of experiments exceptional 
opportunities were offered for infection of the culture medium by 
air borne cysts, ete., to occur, and the resulting protozoan fauna 
shows that the atmosphere is a negligible factor in the seeding of 
hay infusions used for laboratory study. 
W series. The data from the W group of infusions show the 
protozoan life which was introduced with the laboratory tap 
water. Wy1 showed from the start heavy growths of Chilo- 
monas, Oikomonas, and Chilodon, and these persisted in varying 
numbers until November 9th. At this time the culture was 
seeded with paramaecia and two days later there was a con- 
siderable increase in their number. The culture was discontinued 
at this time. In the Wy2 infusion there appeared several species 
of monads, including Oikomonas and Bodo. A rotifer (Rotifer 
vulgaris) was observed on August 12th and increased in numbers 
until there were about 2000 per cc. at the top of the infusion, when 
the culture was discontinued on November 11th. The culture was 
seeded toward the end with paramaecia which multiplied rapidly. 
Wti and Wt2 developed numerous species of monads and also 
considerable growths of a tiny amoeba. Wt had as many as 
5000 per cc. when it was lost by an accident on September 2nd. 
Wt2 on the same day had 20,000 amoebae per cc., and on Septem- 
ber 24th these were succeeded by myriads of Amoeba radiosa. 
The culture was seeded with paramaecia on November 9th, and 
was destroyed on November 11th when it contained a good cul- 
ture of this animal. Wy3 and Wt3 remained plugged, as a con- 
trol, until November 9th and when examined on this day they con- 
tained practically the same fauna as the other cultures of the W 
series as described above. A point worthy of special note, how- 
ever, is that Wt3 showed, in addition to many tiny amoebae, 
about twenty-five Amoeba proteus per cc. of the fluid at the top 
of the culture. It is interesting that in certain cultures heavy 
growths of tiny amoebae appeared; that in one culture these gave 
place to radiosa forms; and in a third, Amoeba proteus appeared. 
This suggests the possibility that Amoeba proteus was introduced 
in the form of extremely minute spores which became apparent as 
tiny amoebae, later became amoebae of the radiosa type, and in 
