459 
The Conjugation of the Infusoria . 
The pole-nuclei must therefore be spores, and the process, 
i.e. the two divisions at B and C, must be a spore-formation. 
The proof of this would undoubtedly be the discovery that in 
these two divisions — probably in the second one — a reduction 
of the number of chromosomes was accomplished. 
The evidence that this happens is at present not quite 
complete. In Paramecium ) where, as will be seen, quite similar 
processes occur (woodcuts io and ii, B and C), it is certain 
that prior to conjugation a reduction does occur. R. Hertwig 1 
states that the stationary and the wandering nuclei, i.e. the 
like gametes (, d ), possess each 4-6 chromosomes, and he 
describes the normal number of chromosomes in the micro- 
nucleus of P. aurelia as ten 2 . 
Of the four spores produced in each individual ( Colpidium ), 
all but one atrophy. 
The spore-individuals or sporozooids do not themselves 
conjugate, but by virtual fission, in which the individuals 
produced do not become separate, because there is no division 
of the protoplasm, like gametes or gametozooids arise. The 
sexual generation thus arises from the spores, or asexual 
generation, by fission 3 . Thus the antithetic alternation is 
recognizable here ; but, and all this holds true for the other 
Infusorians to be afterwards considered, it is largely masked 
to observation and detection, because overshadowed by the 
process of fission, which has become so highly evolved among 
the Infusoria. 
Other Infusoria present slight differences in the conjugation 
processes, and, in order to demonstrate how, mutatis mutandis , 
the ‘ law * holds for all, short interpretations of various cases, 
figured by Maupas and worked out by him and by R. Hertwig, 
may now follow. 
P aramecium aurelia (woodcut 10). This form possesses 
two micronuclei. The conjugation is explained as follows. 
1 Loc. cit., p. 182. 2 Loc. cit., p. 184. 
8 Subsequent to actual conjugation the cycle contains a great but, as Maupas 
has proved, definite number of secondarily asexual generations, but with duplicated 
chromosomes, produced by fissions. 
