﻿399 



What the limits of the ontocycle may be has not yet been ascer- 

 tained, but so far as the facts are known it would appear to be coin- 

 cident with the limits of agamic reproducti on, or, in other words, 

 with the limits of the growth of one autotemnon or of one ovum 

 after cojugation by fission, and includes all agamic generations pro- 

 duced by division or by budding. 



The act of self-fission is similar whether it takes place for a cer- 

 tain cycle among Protozoa or Metazoa under purely organic condi- 

 tions or follows upon the conjugation of two zoons, and is due to 

 the rejuvenation caused by the union of the nuclear elements of 

 their bodies as among Protozoa, or the more differentiated genera- 

 tive cells of the Metazoa. Under all conditions the cells divide in 

 obedience to the laws of growth, and whether the resulting daugh- 

 ter cells remain fastened together forming colonies as in Protozoa 

 or masses of tissue as in Metazoa, or whether they separate and 

 become distinct autotemnons or distinct zoons the action is the 

 same. 



The product of this autotemnic function in single cells has, as 

 shown by the researches of Maupas, a cycle of transformations 

 which are like those of an individual among Metazoa, although 

 they may reach in some forms over six hundred so-called genera- 

 tions and therefore include thousands of distinct protozoans. It is 

 obvious to the student of bioplastology in reading Maupas' re- 

 searches * that this cycle among Protozoa Ciliata is the equivalent 

 of the cycle of the individual among Metazoa. Although he uses 

 the word individual for the autotemnon he does not speak of the 

 successive forms as generations but as partitions, " bipartitions " 

 being his usual term, showing clearly that he recognizes these are 

 not generations like those of distinct successive zoons in Metazoa. 



Maupas' researches show, as in fact he himself states, that there 

 is a cycle of partitions produced from one autotemnon after conju- 

 gation, when isolated and allowed to propagate by fission without 

 the renewed stimulus of conjugation with others of different broods. 

 The earlier successive partitions are incapable or at any rate do not 

 show any desire to conjugate with their fellows. Each of his cul- 

 tures of isolated autotemnons passed through these youthful or 

 anaplastic stages, and then a series of metaplastic partitions was 

 developed in which the micronuclei became more numerous and 



* " Recherches exp<Srimentales multiplication des infusoires cilics," Archiv, de zool. 

 exper. et gen., S6r. 2, Vol. vi, pp. 165-277 ; ibid., Vol. vii, pp. 149-517. 



