Abstract
Woodruff and Erdmann in 1914 1 described a normal periodic reorganization process without cell fusion, which they termed endomixis, in Paramaecium aurelia. This study was based chiefly on pedigreed cells from Woodruff's 5,000-generation race of Paramaecium aurelia, though specimens of a race of this organism isolated by Erdmann in Germany showed the same phenomenon.
The present communication is to prove the general occurrence of endomixis in races of Paramaecium aurelia, since this has been questioned, on a priori grounds, by certain authors.
The following races of Paramaecium aurelia, in addition to those mentioned above, have now been studied:
Oberlin Race. Isolated at Oberlin, Ohio. Carried in pedigreed culture from October 8, 1914, to date, during which time it has attained 951 generations.
Bryn Mawr Race. Isolated at Bryn Mawr, Pa. In pedigreed culture from January 7, 1915, to February 8, 1916, when it was discontinued at the 650th generation.
Oxford Race. Isolated at Oxford, Ohio. Pedigreed culture started on July 16, 1915, and has to-day (May 24, 1916) attained the 779th generation.
Woods Hole Race. Isolated at Woods Hole, Mass. Pedigreed culture begun on August 11, 1915, and discontinued on January 14, 1916, at the 305th generation.
Each of the above races has shown endomixis at the regular rhythmic periods throughout its culture and therefore this additional data from races from diverse sources fully corroborates the statement of Woodruff and Erdmann 1 that “this reorganization process is a normal phenomenon and probably occurs in all races of the species Paramaecium aurelia.”
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