230 V. A. DOGIEL 



The macroconjugant, transformed into a fertilized female, 

 will thus go on living and multiplying, while the microconjugant, 

 now to be regarded as a dwarf male, is predestined to die after 

 conjugation. 



It is very interesting to note that the sexual phases of 

 . j a n u s remind us of the reproduction in a group of Metazoa, 

 namely, in some of the Cirripedia. It is well known that 

 several representatives of the Cirripedia possess, besides the 

 large hermaphrodite individuals, so-called complementary 

 dwarf males. I cannot help comparing the macroconjugants 

 of 0. janus to hermaphrodite Cirripedia, while the micro- 

 conjugants are on the way to become complementary males. 



Another point worthy of special mention is the progamic 

 fission. Several species of Infusoria (D i 1 e p t u s , D i d i n i u m , 

 Paramecium, &c.) are known to undergo, before conjuga- 

 tion, several ' hunger-divisions '. R. Hertwig, postulating 

 a causal connexion between these divisions and conjugation, 

 says that hunger-divisions may correspond with the maturation 

 divisions of multicellular organisms. Still, it is uncertain how 

 far these divisions are indispensable for the beginning of con- 

 jugation, and how far the preconjugants differ from the 

 ordinary (neuter) individuals. All the Ophryoscolecidae 

 examined, and 0. janus more than the rest, prove that the 

 fissions preceding conjugation have a peculiar character. They 

 have a close connexion with the commencement of sexual 

 reproduction and must bear the special name of progamic 

 fissions. The individuals resulting from these fissions are the 

 preconjugants, which differ in several points from the 

 neuters. Only the preconjugants are able to conjugate ; and 

 this compels us to consider the progamic fission as a process 

 which may be compared with the attaining of puberty by 

 multicellular organisms. The individuals which are formed by 

 the progamic fissions are sexually mature. On the other hand, 

 the reduction divisions of the micronucleus during conjugation 

 are the real homologues of the maturation processes of sexual 

 cells in the Metazoa. 



The same rule — that conjugation is possible only between 



