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THE AMERICAN NATURALIST 



[Vol. LI 



Auerbacli and Parisi try to show that a real syncaryon 

 formation takes place at the onset of spore formation. 

 Other authors, Keysselitz, Schroeder and Auerbacli, be- 

 lieve that only a plasmogamy can be pointed out at the 

 beginning of spore formation, and that the union of the 

 nuclei is effected either in the fully developed spore or 

 in the young animal leaving the spore. The difference 

 between these last two conceptions is theoretically with- 

 out significance because the main part of copulation— the 

 union of the nuclei— takes place at the onset of the neiv 

 life cycle of the myxosporidimi. Therefore it was of 

 the utmost importance for decisive proof of this fact 

 to find the copulation of the two gametonuclei inside 

 the fully developed spore or in the young myxosporidian. 

 Schroeder, 1909, observed the copulation of the two game- 

 tonuclei in the spore; Auerbach, 1907 and 1910, found 

 young animals of Myxidium hergense with one nucleus. 

 I was able to demonstrate young Chloromyxum leydigi 

 which were experimentally x>roduced by placing the two- 

 nucleated spores on gall plates (Erdmann, 1911). Here, 

 after a treatment with intestinal secretions of the host 

 the young animals leave the spore. They are at first bi- 

 nucleate, later uninucleate. In my recent work, finished 

 in 1913, which did not appear until 1917 in consequence 

 of the war, I figured these young animals after fixation 

 and staining. Also, Davis, 1915, though with some re- 

 serve, presents young Spharospora dimorpha which have 

 left the spore and show the fusion of their two nuclei. 

 Later the separation of the syncaryon into its vegetative 

 and generative components takes place. Georgevitch, 

 1914, presents the development of the young animal in 

 Henneguya gigantea in— as it seems— changed pecu- 

 liar conditions. The spore is still inside of the cyst of the 

 big "tumor-forming" tissue-parasite. The binucleate 

 form becomes uninuclear and then the usual vegetative 

 multiplication of the nuclei begins, which leads up to a 

 renewed spore formation inside of the tumor cyst. In 

 Chloromyxum leydigi, a gall-bladder parasite, no such 



