THE OPALINID CILIATE INFUSOEIANS. 



105 



abnormal conditions, several peculiar phenomena appearing. Among 

 these, rounding up of the macrochromosomes is often seen, 



Zelleriella patagoniensis is much like Z. pahcdicolae, but in my in- 

 fections is larger and its body form is different in some individuals. 

 Figure 71, c, shows an individual of a form very frequent in Z. pata- 

 goniensis, but not observed in Z. paludicolae. The comparison be- 

 tween these two species is something like that between Protoopalina, 



Fig. 71. — Zelleriella patagoniensis, X 460 diameters. 



caudata and P. intestinalis. The pointed tip, or posterior process, 

 so often seen in P. caudata^ though not in all individuals, is one of 

 the most characteristic things in that species and is not observed in 

 any individuals of P. intestinalis. Similarly, many, but not all, in- 

 dividuals of Zelleriella patagoniensis show the definite posterior pro- 

 cess, short and flat, to be sure, in this fiat species, while in Z. paludi- 

 colac no such posterior process is found at all well developed. 



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