196 LORANDE LOSS WOODRUFF AND HOPE SPENCER 



But sooner or later the two merge into one large vacuole. In 

 this regard our animals are exactly similar to those in Moody's 

 cultures. 



Nuclei. The nuclear apparatus of Spathidium as exhibited 

 by our animals is remarkably variable, though it agrees, in the 

 main, with the description given by Maupas. The typical 

 vegetative cell apparently contains two long ribbon-like macro- 

 nuclei which extend nearly the whole length of the cell (fig. 

 11). However, owing to the intertwining of these bands, we 

 have been unable to decide whether they are actually distinct 

 or whether they are united at the posterior end to form a single 

 structure. It seems probable that both conditions occur be- 

 cause the macronucleus varies considerably from day to day; 

 very many otherwise typical animals showing the macronucleus 

 fragmented into a few or many separate pieces. Thus far it has 

 not been possible to associate these morphological macronuclear 

 changes with characteristic events in the life-history. 



Maupas states that there are from six to nine micronuclei 

 present in Spathidium and the same is apparently true for the 

 organisms of our culture. Seven are visible in the animal illus- 

 trated in figure 11. In the majority of cases they are difficult 

 or impossible to identify owing to the fragmented condition of 

 the macronuclear apparatus and the presence of remnants of 

 the nuclei of ingested Protozoa. 



Moody was unable to discover any micronuclei in the animals 

 of her culture and states: "Although it is generally thought 

 that the possession of two types of nuclei is characteristic of the 

 ciliates, the present observations give no evidence of this differ- 

 entiation in Spathidium. "21 In this connection it is important 

 to note that Moody says : " Conjugation was not observed, though 

 numerous attempts were made to bring it about." From the 

 standpoint of the micronucleus, then, JMoody's animals were 

 characteristically different from those of our cultures, which 

 not only are micronucleate, but the micronuclei function in a 

 typical manner during conjugation. Indeed, the chief value 

 of the animals of this culture is the ease with which they may 



21 G. N. Calkins, The Protozoa, 1901, p. 358. 



