457 
The Conjugation of the Infusoria. 
The one fact that would be fairly decisive appears to be 
lacking, or, at any rate, incompletely known. This is as 
to the precise point at which the chromatin-reduction takes 
place. 
Theoretically, as will be presently proved, such a reduction 
at some point or other must be postulated even here. How- 
ever, from R. Hertwig’s statements the actual point can be 
fixed upon with a fair degree of certainty, and, as will be 
evident, it would appear to lie at a certain phase of the 
conjugation which a priori seems to be a very likely one. 
Amoeba , Gregarina , &c. — in fact a great many far simpler 
Protozoa than Paramecium , apart from fission, exhibit a 
simple process of conjugation, leading to encystment and 
spore-formation. Such a process, however simple it may be, 
must entail a reduction of chromosomes prior to the next 
conjugation. 
Although there appear to exist no direct observations 
on such a reduction in these cases, there is practically no 
doubt that it takes place at the spore-formation following 
conjugation and encystment. Otherwise the spore-formation 
would be without meaning ; for these forms can multiply 
in a very rapid manner by simple fission alone. Such a 
conjugation as the above must be a very primitive form of 
an alternation, and, indeed, one in which a zygote or gameto- 
zooid hardly can be said to possess a separate existence for 
any lengthy period ; because the spore-formation and reduction 
follow almost immediately on the conjugation and duplication. 
Paramecium is morphologically a far more complex organ- 
ism. It presents more than one nucleus, and division of labour 
among these. As in Amoeba , we recognize here two processes 
of multiplication — fission and conjugation 1 . 
Colpidium colpoda (woodcut 9) is usually cited as affording 
one of the simplest examples of conjugation, and it may 
therefore be the first form to be examined. 
Turning our attention to the processes that occur after 
1 Spore-formation is not a distinct and separate mode of reproduction, but is a 
necessary corollary to conjugation. 
