PROTOZOAN FAUNA OF HAY INFUSIONS 207 
fauna of hay infusions is preliminary to further studies on the 
interactions of particular species on each other. 
Il. ORIGIN OF THE PROTOZOAN FAUNA OF HAY INFUSIONS 
The point first considered was the source or sources from which 
the protozoa which appear in infusions of hay are derived. This 
general problem has, of course, been treated at length in the long 
series of experiments on spontaneous generation which occupied 
the attention of biologists for several centuries. The present 
experiments were planned to determine the best method of making 
up infusions for the purpose of the study of their biological cycle, 
and incidentally to show the relative importance of air, water and 
hay, and whether some forms appear in infusions chiefly through 
one of these channels and others through another. 
Hay is generally considered the chief source of the protozoan 
life of infusions. Kent? in 1879 studied the question 
from. whence (are) derived all these myriad organisms frequently pro- 
- duced in such abundance as to literally jostle each other for room in 
every drop of water extracted forexamination? . . . . hayfrom 
different localities was placed in maceration and examined continuously 
from its first contact with the fluid medium, from periods varying in 
duration from a few days only to several weeks. The water added to 
the hay was of the purest possible description, and was frequently boiled 
for some time to prevent the introduction of extraneous germs. In all 
instances, the results obtained were broadly and fundamentally the same, 
and differed only with respect to the specific types found living together 
in the separate infusions. Even here, however, the general dominance 
of two or more special forms was notably apparent. 
Kent was satisfied, then, that the organisms were derived from 
the hay, and microscopical examination of the mode of distribu- 
tion of the cysts upon the lowermost blades, colored brown or 
yellow from incipient decay, led him to conclude that ‘‘all the 
essential conditions of their life cycle had been passed in close 
connection with it.’”’ He put this conclusion to a practical test 
by gathering grass saturated with dew during a heavy fog and 
studying it without the addition of any water. 
3 A manual of the infusoria. London, 1880, pp. 135-141. 
