PHYSIOLOGICAL DEGENERATION IN OPALINA. 639 



detected^ and very commonly small buds are given off wliicli 

 contain an eosinopliile globule, but no nucleus. All these 

 enucleate buds appear to die and disintegrate. Finally, a 

 number of uninucleate atrichous forms result, which are of 

 an average diameter of about 20 fx. At this stage they show a 

 marked tendency to attach themselves to one another, thus 

 forming small colonies (cf. Plate, fig. 12). No fusion, as a 

 rule, appears to take place. 



The chromatin of the nucleus, which is of a very variable 

 size, but on an average about 8 — 10 ju in diameter, is seen to 

 be arranged in lumps peripherally. It soon leaves the 

 nucleus, however, and fills the cytoplasm, where it takes the 

 form of irregular granules and masses of different shapes 

 and sizes. These chromidia, as they may be called, appear 

 to be sometimes in the form of minute hollow spheres, ring- 

 like in optical section. By their formation the original 

 nucleus dwindles away, and finally disappears (see Plate, 

 figs. 1, 2, 7). As a rule most of this chromatin is cast out of 

 the organism, which then dies and breaks up. But occa- 

 sionally a remarkable thing happens. Only a part of the 

 chromatin is cast out and perishes. The remaining granules 

 run together again, very much as drops of oil might run 

 together in a watery medium. All the irregular chromidia! 

 masses may become aggregated at a single centre, but at 

 other times two such centres are formed, so that finally two 

 nuclei, consisting of solid chromatin, are synthesised. These 

 two solid lumps then approach one another and fuse (see 

 Plate, figs. 3 — 6). During the chromidial stages a soft cyst- 

 wall is sometimes formed. 



I have been unable to obtain any further stages after this, 

 except such as are disintegrative. Kept under a waxed 

 coverslip or in a hanging drop they always perish by 

 discharging their nuclei in fragments and then breaking up. 

 This also appears to happen in the frog^s gut. It would be 

 exceedingly interesting to know whether a recovery could be 

 made under suitable conditions or not. I have endeavoured 

 to restore some of these degenerate fragments by transfer- 



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