SEXUAL PHENOMENA IN THE PROTOZOA 



241 



Attention may again be called to the fact, repeatedly observed by 

 Biitschli, Engelmann, Gruber, Maupas, and others, upon the Infuso- 

 ria, that if conjugation is prevented, continued cell-division leads to 

 degeneration, and that this process is cumulative, resulting eventually 

 in the atrophy of external and internal organs (including vibratile 

 membranes, cilia, micronuclei) and, finally, in death. " There is no 

 question," says Butschli, "that conjugation is a process which, if pre- 

 vented, leads to death of the ciliates, just as a race of Metazoa dies 

 out if restrained from sexual reproduction. 1 " The cell-body becomes 



A B . C 



Fig. 132. Onychodromus grandis Stein. [MAUPAS.] 



A. Normal individual. B. Smaller form without micronuclei ; degenerate. C. A still more 

 reduced and degenerate form. N, macronucleus ; n, micronucleus. 



smaller, more plastic, and less resistant, and assumes various irregular 

 shapes (Fig. 132). If degeneration has not gone too far, the normal size 

 of the individual, the organs, and the general vitality are restored by 

 conjugation, which is effected through the union of the soft mouth 

 parts, while the internal phenomena consist of the interchange of 

 micronuclei and possibly of some cytoplasm. 2 The phenomena of 

 degeneration may therefore be considered in two categories : (i) the 

 effect upon the plasm and the form of the cell-body ; (2) the effect 

 upon the nuclei. The former, I believe, leads to the reduced size of 

 the conjugants, the latter to the so-called maturation in Protozoa. 



('88), P . 1638. 



2 Cf. Maupas ('88), Butschli ('88). 



