THE OPALIXID CILIATE INFUSORIANS. 



21 



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tween Neresheimer's observations and my own and there are certain 

 gaps which no observations cover. I had hoped to obtain ere this 

 material for following these phenomena in detail, but circumstances 

 beyond control have hindered my plan for obtaining the needed ma- 

 terial in the Tropics. I will here describe the phenomena as 

 observed, noting the 

 gaps and discrepan- 

 cies. Neresheimer de- 

 scribed for multiim- 

 cleate Opalinidae a 

 period before the 

 rapid spring divisions 

 begin, during which 

 the nuclei give off nu- 

 merous chromidia in- 

 to the cytoplasm and 

 then degenerate and 

 disappear. Mean- 

 while new nuclei 

 gradually form from 

 the extruded chro- 

 midia and these be- 

 come the definitive 

 nuclei during the fur- 

 ther life of the ani- 

 mal. In my studies 

 of Protoopalina intes- 

 tinaJis and P. caudata 

 (see Metcalf, 1909) I 

 did not find any such 

 degeneration of nu- 

 clei, except in the case 

 of a few individuals 

 of P. caudata which 

 were interpreted as 

 abnormal. In recent 

 studies of 7,000 slides 

 of 150 species, I find 

 in two species of binucleated Opalinids, Zelleriella Jilrsuta (new) 

 and Z. [of Btifo woodkousi] (new), degeneration (?) phenomena (figs. 

 99 and 100, pp. 135 and 136, and fig. 98, p. 132) apparently related to 

 those Neresheimer described in several multinucleated forms.^^ They 



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Pi.; 9. — Protoopalina intestixalis ; showing reduc- 

 tion IN THE NDMBEK OF MACROCHKOMOSOMES. X 673 

 DIAMETERS. 



'3 In a former paper (Metcalf, 1909) I described in some detail degeneration phenomena 

 in the nuclei of Opalina ohtrigona. 



