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LORANDE LOSS WOODRUFF 
4. Factors determining the sequence 
The problem becomes enormously complex when an attempt is 
made to decide upon the chief determining factors of the observed 
sequence of organisms at the surface of the infusions, and is en- 
tirely beyond our power of analysis from the data extant. There- 
fore, I believe, it is preferable at this time not to enter into an 
extended discussion of this question. I shall, however, briefly 
mention some points which seem to indicate suggestive lines for 
future study. 
There is experimental evidences that, broadly speaking, the 
potential of division decreases from monads to paramaecia; that 
is, for example, paramaecia, under optimum conditions, divide 
less frequently than the majority of the hypotrichida, and simi- 
larly, the latter divide less rapidly than Colpoda. In regard to 
Vorticella and Amoeba, however, sufficient data are not at hand 
to make a definite statement. 
With this in mind a series of experiments were made on the time 
of appearance of maximum numbers of Monads, Colpoda, Hypo- 
trichida and Paramaecium in separate flasks of infusion which 
were seeded with a single individual of one species. The multi- 
plication of the respective forms in the various flask cultures was 
observed, and the results showed remarkable agreement with the 
sequence of maximum numbers as determined for these same 
forms in the regular infusions. Consequently it appears that the 
number of specimens of any particular organism initially intro- 
duced into the large infusions, or the time of emergence of en- 
cysted forms has not had an important influence on the sequence 
of maximum numbers in these infusions as determined for the 
complete series. It may well, however, account for at least some 
of the individual variations in the sequence of appearance in 
numbers sufficient to be included in the samples studied, and of 
maximum numbers, which are apparent in particular groups of in- 
fusions. Again the interaction of the different forms would 
appear, at first glance, not to be a crucial factor in the sequence 
of maximum numbers since, in the experiments cited, the ‘se- 
‘quence’ was duplicated, when only one species of organisms was 
