NEW INTERPRETATION OF CNIDARIA 303 



but even more so in the qualitative direction; the karyons 

 had become differentiated in spite of their total potentiality 

 after they had assumed a certain place in the animal 

 body, a development which was of the greatest import- 

 ance for the prospective destiny of the Eumetazoa. This is 

 the reason why there is no macronucleus in the Acoela, this 

 is one of the key differences between the higher Infusoria 

 and the lowest Acoela. It must necessarily be supposed that 

 formerly there had also existed intermediate forms between 

 the stage with numerous vegetative karyons and the stage 

 which has one karyon only and which is the final stage 

 reached by way of this oligomerization. Not only in such 

 stages was the number of karyons decreased, but even their 

 behaviour was different (the type of origin, the subsequent 

 divisions, etc.). The macronucleus, however, has lost its 

 total potentiality and it has to be newly formed after 

 each conjugation (combined with a copulation) when the 

 final stage of the oligomerization has been reached and 

 when everything has become concentrated in the macro- 

 nucleus. 



The case of Kemanella which has been pointed out by 

 Hanson is certainly very interesting because here the macro- 

 nuclei are not developed by way of a division of themselves, 

 but instead they develop continually from the micronuclei 

 which themselves are also able to multiply. It is quite possible 

 that a more primitive stage is represented in this case, even 

 if a special development cannot be excluded either. The plau- 

 sibility of my concept again does not depend on all this. 

 Hanson states, "It can be seen that nuclear situation in 

 Kemanella provides a transitional form in a possible series 

 going from that typical of the ciliates to the dispersed nuclei 

 of the acoels" (Hanson, 1958 : 37). At the same time he adds 

 that this series can also be reversed which, however, is not 

 probable for other reasons. I confidently expect that new 

 material evidence will come to light during the future studies 

 of Infusoria which will support our thesis. 



