246 LORANDE LOSS WOODRUFF 
those protozoa, like Paramaecium, which are strong swimmers 
are most frequently found in this region. 
VI. PROTOZOAN FAUNA AT THE BOTTOM OF THE INFUSIONS 
On account of the marked difference in the bottom fauna of the 
A, B, and C infusions, it is more convenient to consider each of 
these types of infusions separately. 
1. A Infusions 
Monad. The types of monads recorded in the surface fauna 
were observed in inappreciable numbers at the bottom, so that it 
is evident that when these forms disappear from the surface their 
cycle is over. Certain other species of monads appeared irreg- 
ularly in comparatively small numbers at the bottom, but it is 
unnecessary to recount them here. 
Colpoda. In groups I and II Colpoda did not appear at all at 
the bottom. In group III comparatively few Colpoda (approx- 
imately one-twenty-fifth as many as at the top) appeared just 
during the top maximum. Group IV showed a maximum of 500 
per ee., which coincided with the top maximum of 2500 per ce. 
Hypotrichida. These forms occurred in negligible number in 
groups II, II] and IV. In group I there was a small maximum of 
60 per ce. on the 38th day. 
Paramaecium. Practically no paramaecia appeared at the 
bottom in any of the A cultures except A2, where, toward the end 
of the observations, one count of 300 per cc. was taken. 
Vorticella. Vorticella were not observed in group I until near 
the end (76th day) when a maximum of 40 per cc. was attained. 
Group II, however, showed the largest number for the A series, 
with a maximum of 400 per cc. on the 72nd day, 1.e., near the end 
of the observations. In groups III and IV Vorticella was not 
observed until nearly the end of the study when maxima of about 
40 per ce. were reached. 
Amoeba. In all the groups of infusions, amoebae were in greater 
abundance at the bottom than at the top. A maximum of 3000 
per ce. occurred from the 55th to the 60th day in A J; a maximum 
of 6000 per cc. on the 76th day in A JJ; a maximum of 2000 per 
