726 



THE AMERICAN NATURALIST [Vol. LI 



spore membrane-forming cells, the other forms the two 

 capsulogenous cells and two gametes. We intentionally 

 avoid, in Fig. 3, calling 

 ft the two chromatin 



lumps, which the author 

 himself (p. 202) 'has 

 g g called "iiberfliissiges 



^figl Al2 Chromatin ' ' ( degenerie- 



o ^ rende Kerne), nuclei 



^21. A22 and do not add them 



A A fl ^^^^ diagram 



Am ^A121 as Auerbach, 1912, p. 



^the ^spo^e'"^m^mbrane-Wrm\ng°*^cens 28, did wheU disCUSSiug 



(valve cells). An. -4 '"'^j^"'^ J^^^^g^j^^' Awerinzcw's investiga- 



and A^n are the capsulogenous ce s. ^.^^^^^ COUSidcr 



these chromatin lumps only as formations probably of 

 glycogenous nature and as being used during membrane 

 formation. 



In Fig. 4 Auerbach 's conception (Type I) of how 

 the spore formation is effected in Myxidium bergense is 

 represented. Auerbach believes, as stated before, that 

 either a plasmogamy (Type I) or a real copulation (Type 

 II) may be at the basis ^ 

 of spore formation. We -^Bl 

 will not discuss, for the 0^^ 

 present, how the bigger 

 and smaller cells which ^ 

 are seen at the l)egin- 

 ning of spore forma- 

 tion, arise. The latter ®Bt1 "^Bll 

 divides once and the Q Q 

 two divisional products Am ^A\tl A121 A122 

 form the spore-mem- >• Mif.n'Uum hcr,„nsr (Au.t- 



brane-forming cells. Tlie membrime-formlng'cells (vi'i'ive cells). Am 

 other cell divides twice -'^^^ aVe^'thrcapsullge^'nourcens' ^""^ 



to give rise to two gam- 

 etes and two capsulogenous cells. The author does not 

 especially mention the order in which these cells divide, 



