THE OPALINID CILIATE INFUSOEIANS. 133 



come from longitudinal division, with one large dumb-bell nucleus 

 and several small " nuclei " of varying sizes (5) (this significant in- 

 dividual will be discussed further) ; 4, a daughter cell from trans- 

 verse division with two spherical daughter nuclei and four small 

 *' nuclei " (e) ; and 5, a small cell with two small nuclei {d). In this 

 species and in Z. hirsuta, next to be described, we find phenomena of 

 nuclear degeneration (?) which may be related to those described 

 by Neresheimer (1907) for Cepedea dimidiata and Opalina ranarum. 

 He reported the formation of abundant chromidia, the subsequent 

 degeneration of the original nuclei, and the formation of new nuclei 

 from the chromidia, these newly- formed nuclei persisting and func- 

 tioning during the sexual phases of the life cycle. 



I have not had living material for following these phenomena, 

 and am in some doubt whether the conditions found in these two 

 species of ZeUeriella are really normal phenomena of the life cycle, 

 as Neresheimer describes, or are abnormal, perhaps associated with 

 parasites of the Zelleriellas. The latter seems the more probable. 

 It is hardly profitable to discuss the matter at any length here, for I 

 hope to obtain living material of one of the species, Z. hh'suta, for 

 further study. A few words of comment, however, seem called for. 

 Figure 98, 5, shows a daughter cell with large nucleus in active mito- 

 sis, and also several small " nuclei " of varying sizes. Figure 98, e, 

 shows a daughter individual which has passed into a little more ad- 

 vanced condition after fission, its two major nuclei being now dis- 

 tinct, but four other " nuclei," small, are present. We thus see that 

 if the small nucleuslike bodies are true nuclei, formed from chro- 

 midia, as Neresheimer reports for two multinucleated species, the 

 extrusion of the chromidia, which must have taken place some con- 

 siderable time before, has not been followed as yet by degeneration 

 of the original nuclei. These have persisted and have gone on divid- 

 ing. On the contrary, when we come to the description of Z. hirsuta 

 we will see that what appear to be the original nuclei do change their 

 appearance in a way seeming to indicate their degeneration, and this 

 is also true of the individual of the present species shown in figure g. 



In my prolonged and detailed studies of Protoopalina intestmalis 

 and P. caudata (Metcalf, 1909) I did not find these phenomena of 

 apparent degeneration. I did find nuclear degeneration in Opalina 

 ohtrigona, but interpreted it as abnormal. The conditions for ob- 

 servation are so much better in binucleated Opalinids that it is im- 

 portant that these phenomena, if they occur, be studied thoroughly in 

 them. At the same time the behavior of each of the two sets of chro- 

 mosomes, massive and granular, should be observed in detail. The 

 Zelleriellas are especially favorable for such study, for they have 

 large nuclei and flat bodies, so that in smear preparations cytological 

 detail can be seen almost as well as in sections. I hope to undertake 



