ENDOMIXIS 



649 



and the transformation of one or two of the products of the micronuclear 

 divisions into new macronuclei, to reconstitute the normal vegetative 

 apparatus when distributed by cell division (Figs. 155, 156). 



Immediately after this announcement, Hertwig (1914) described 

 similar phenomena in P. aurelia as parthenogenesis, induced, he believed, 

 by degenerative changes, and emphasized the fact that in his study of 

 conjugation in this species (1889), he had noted stages in certain non- 

 con jugants that were open to a similar interpretation. Thereafter en- 



Figure 156. Possible methods of micronuclear and cell division at the climax of endo- 

 mixis in Paramecium aurelia. lb is typical. (From Woodruff and Erdmann, 1914, p. 448.) 



domixis, or, if one prefers, diploid parthenogenesis, was reported by 

 many investigators, including Erdmann and Woodruff (1916) in P. 

 caudatum, Calkins (1915, 1919) in Didimum nasutum and U role plus 

 moh'tlis, Moore (1924) in Spathidium spathula, Erdmann (1925) in 

 P. hursaria, Woodruff and Spencer (1923) in P. polycaryum, Klee 

 (1925) in Euplotes longipes, Ivanic (1928, 1929) in Chilodonella 

 uncinatus, Vortkella nebulifera, Euplotes charon, and £. patella, Man- 

 well (1928) in Pleurotrkha lanceolata, Diller (1928) in Trichodina 

 sp., Chejfec (1928, 1930) in P. caudatum, Faure-Fremiet (1930) in 

 Zoothamnium alternans, Stranghoner (1932) in P. mult'miicronucleatum, 

 Tittler (1935) in Urostyla grandis, Kidder (1938) in Paraclevelandia 

 simplex, and Gelei (1938) in Paramecium nephridiatum. In most of 



