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THE AMERICAN NATURALIST [Vol. LI 



which are supposed to prove the merging of two cells, 

 they can, as said before, be interpreted as the division of 

 one cell into two. The larger of these cells, wrongly 

 called macrogametocyfe according to the cell fusion 

 theory, has divided and formed the cell wrongly called 

 microgametocyte. 



This ''microgametocyte" and its division products after 

 one division, or these "microgametocytes" in cases where 

 two gametocytes are observed at the onset of spore for- 

 mation (Keysselitz, Schroeder, and Erdmann) now form, 

 according to all known investigations, the pansporoblast 

 membrane. Just as we could point out in disporous 

 forms the uniformity of the origin of the spore-mem- 

 brane forming cells (Figs. 2, 3 and 4) so we can do the 

 same for the pansporoblast membrane and its nuclei in 

 the following forms: Myxoholus pfeifferi (Keysselitz), 

 Myxoholus ellipsoides (Lo Giudice), Sphceromyxa sa^ 

 hrazesi (Schroeder), Sphcerospora caudata (Parisi), Hen- 

 neguya gigantea (Georgevitch), and Hermeguya psoro- 

 spermica (Auerbach) ; all following Fig. 5, provided 

 we do not take into consideration the origin of the 

 cells A, A2 and B and Keysselitz and Schroeder 's 

 views, except one contradictory point, are exactly repre- 

 sented by Fig. 5, but there are differences mentioned 

 by the other authors. Still we make the generalization 

 that there is one and the same plan of spore formation in 

 the pansporoblastic myxosporidia though we know that 

 facts are reported which do not fit in with our view. We 

 hold the opinion that it is permissible to rearrmge the 

 observed facts, beca/use all interpretation have been 

 gained by piecing together and arranging facts according 

 to the theoretical viewpoint of the authors. No continued 

 observation of spore formation in the living animal has 

 been possible. Also we are allowed to add facts ascer- 

 tained in other species if the authors have only consid- 

 ered sections and not smears. Sections are misleading 

 because the whole quadruple group can not always be seen 

 on the same section and the origin of the small cell fro. 



