100 C. CLIFFORD DOBELL. 
Polytoma by Prowazek (86). Dallinger and Drysdale (12) 
also stated that more than two monads might unite, previous 
to sporulation, in Bodo, although this has never been con- 
firmed. 
The points of special interest in the conjugation and con- 
sequent events in Copromonas are the nuclear reduction and 
the fate of the zygote. Some general remarks on the former 
subject will be found on p. 111. I will now pass on to the 
later history of the cysts. 
Development from the Cysts. 
Cysts formed in either of the ways described above appear 
to have exactly the same destiny. They are able to withstand 
drying for a considerable length of time, and do not liberate 
their contents until they reach a suitable medium—in this 
case the feces of a frog or toad. 
When the contents of the large intestine of a frog or toad 
is examined, as a rule no monads of this species can be dis- 
covered, After a long and careful search a few cysts are 
usually—though not always—found to be present. Cysts are 
practically always present, probably, although they cannot 
always be found. For if some of the feecal matter be placed in 
a carefully cleaned watch-glass and diluted (see p. 77) a favour- 
able medium for the development of the cysts is formed. In 
the course of a few days—probably in about three days—the 
first monads will be found. When first liberated they differ 
from the adults in their small size, globular shape, and simple 
structure. ‘They possess no reservoir or cytopharynx, and no 
food bodies. The protoplasm is peculiarly pale and trans- 
parent, not at all like the granular protoplasm of the adult. 
These monads develop gradually into the adult form, and then 
begin to divide in the usual way. 
I have not been able to watch the liberation of the monad 
from the cyst, in spite of repeated efforts to do so. I think 
it highly probable that the animal is set free by the cyst 
dissolving, not by its bursting; for I have never seen any signs 
