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saria (Fig. 88). He found that the usual manner of association is 

 conjugation between a pair with the third conjugant attached to the 

 posterior part of one of them (a). Nuclear changes occur in all three 

 individuals, and in each, two pronuclei are formed by three divisions 

 (c) . But the exchange of the pronuclei takes place only between two 

 anterior conjugants (c-e) and autogamy (see below) occurs in the 

 third individual. 



Fig. 89. Diagram illustrating autogamy in Paramecium aurelia (Diller). 

 a, normal animal; b, first micronuclear division; c, second micronuclear 

 division; d, individual with 8 micronuclei and macronucleus preparing for 

 skein formation; e, two micronuclei dividing for the third time; f, two 

 gamete-nuclei formed by the third division in the paroral cone; g, fusion 

 of the nuclei, producing synkaryon; h, i, first and second division of 

 synkaryon; j, with 4 nuclei, 2 becoming macronuclei and the other 2 re- 

 maining as micronuclei; k, macronuclei developing, micronuclei dividing; 

 1, one of the daughter individuals produced by fission. 



Automixis. In certain Protozoa, the fusion occurs between two 

 nuclei which originate in a single nucleus of an individual. This 

 process has been called automixis by Hartmann, in contrast to the 

 amphimixis (Weismann) which is the complete fusion of two nuclei 

 originating in two individuals, as was discussed in the preceding 

 pages. If the two nuclei which undergo a complete fusion are present 

 in a single cell, the process is called autogamy, but, if they are in two 



