NEW INTERPRETATION OF CNIDARIA 297 



as well as in the main line that evolution had taken and which 

 had finally led to the formation of the next higher phylum 

 of Polymeria, we find that the separation of the two sexes 

 had emerged, pairing had been abandoned, and an external 

 fertilization had been introduced. No generally valid regulari- 

 ties or uniformities can be observed in this development. In 

 the Mollusca, for example, we can find at least occasionally 

 a very strong hermaphroditism reintroduced (species of snails 

 with a uniform hermaphroditic gonad) which appears in 

 combination with pairing, with the new formation of organs 

 of copulation, and with an internal insemination and ferti- 

 lization. 



The example of Ophryoscolecidae with their individualized 

 androgametes is not an isolated case among the higher Infus- 

 oria. The androgametes of the hypotrichous infusorian 

 Euplotes patella which has a thickened pellicle assume, ac- 

 cording to Turner (1930), during their migrations, the form 

 of small amoebae and move actively by means of lobopodia. 

 This is clearly a secondary phenomenon. This amoeboid 

 androgamete of Euplotes is not a modified spermatozoon, 

 as this is the case, for example, in Nematoidea or in numerous 

 crayfishes; it is rather a new formation which had evolved 

 from a state of a secondary karyon: in Euplotes no plasmatic 

 bridge can be secondarily developed any longer; the "degene- 

 rated" (retrograded) karyonic androgamete has thus become 

 reactivated, yet this time in a special w^ay. 



The early separation of somatic (vegetative) and sexual 

 karyons is characteristic of the genuine, higher Infusoria 

 from which we do not derive the Acoela. The two game- 

 tic karyons which bear the two opposite signs are developed 

 by way of a heterocyclic division. We find also the macro- 

 and micronucleus developed from a zygote karyon by way of 

 an unequal division. This represents a very advanced specializa- 

 tion, and it has naturally been inherited as such by the Acoela. 

 It must be assumed that the macronucleus is all powerful in 

 spite of its limited function because it receives the complete 



