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THE AMERICAN NATURALIST [Vol. LI 



(Awerinzew) has only an extrusion of chromatin before 

 the syncaryon formation, while in Myxoholus ellipsoides 

 (Parisi) it occurs immediately after this phenomenon. 

 These exceptions in the series, i. e., that inside the spore 

 no chromatin diffusion is observed, may be due in the case 

 of Parisi to a limited number of studied forms and in the 

 case of Awerinzew to the fact that the spore membrane 

 in Ceratomyxa is formed very late. Yet these exceptions 

 do not prevent the final statement that the darkly staining 

 chromatic masses in the spore are not reduction nuclei, 

 or restkernartige Gebilde, but play an important part in 

 the development of the spore membrane. 



The whole trend of our critical review leads up to the 

 following conclusions : 



1. Reduction in myxosporidia has thus far not been dis- 

 covered. 



2. The so-called reduction nuclei inside the spore are 

 chromatic or glycogenous masses, which serve the spore- 

 membrane formation. 



3. The so-called residual nuclei of the disporoblastic 

 forms can not be considered as identical with the somatic 

 residual nuclei of the mono-, di- or poly-sporous non- 

 disporoblastic forms. They are the functionless nuclei of 

 the envelope cells of the disporoblastic forms. 



4. The envelope cells can by their origin only be com- 

 pared with those cells in the mono-, di- or polysporous 

 nondisporoblastic forms which later give rise to the valve 

 cells. 



5. The somatic residual nuclei are well-defined in mono-, 

 di- or poly-sporous nondisporoblastic myxosporidia. 

 Their analogy has not thus far been discovered in disporo- 

 blastic polysporous forms. 



LITERATURE 



Auerbach, M. 1912. Stu.li.M. (Ukt M vx.isporidien der norwegischen 

 Seefische und ihre Verl.roitung. Zoo/. Jahrh. Abt. f. Syst., Vol. 34, 



