Dae LORANDE LOSS WOODRUFF 
after which there was a slight increase up to the end of the obser- 
vations on the 57th day. 
BI group. These forms attained a maximum of 560 per cc. on 
the 11th day, and then very gradually declined until they became 
practically extinct on the 55th day. 
B II group. In this group the maximum of the hypotrichida 
was reached on the 11th day, and extinction on the 29th day. 
B III group. The hypotrichida were practically negligible 
as the maximum number which occurred on the 10th day was less 
than 40 per ce., and the animals disappeared completely by the 
15th day. 
B IV group. Here these forms reached their greatest abun- 
dance, 250 per cc., on the 7th day, declined to about 20 per cc. by 
the 11th day, gradually rose to 150 per ee. on the 26th day, and 
disappeared by the 35th day. 
C I group. In these three cultures the average maximum of 
about 360 per ce. occurred on the 19th day, and was followed by 
a continuous decline until the 49th day, when about 40 per ce. 
were seen. From this time on slight fluctuations in numbers oc- - 
curred, and at the last observation on the 86th day, about 40 
per ec. were still to be seen. 
C III group. In this group, represented by a single infusion, 
these forms first appeared on the 20th day, reached their greatest 
abundance, 300 per cc., on the 24th day, then declined to about 40 
per cc. on the 28th day, and persisted in approximately this 
number to the end of the observations. 
CIV group. Here the hypotrichous forms reached a maximum 
of 500 per cc. on the 32nd day, declined to about 40 per cc. on 
the 37th day, rose to 400 per cc. on the 44th day, declined again 
to about 20 per ce. on the 51st day, and remained at about this 
number to the last observation on the 56th day. 
From the study of the hypotrichous ciliates which appeared 
in all the cultures, it is clear that these forms are adjusted to 
conditions at the surface of the infusions which are present, in 
most cases, after the monads have nearly disappeared and Colpoda 
has passed its period of greatest abundance. 
