D. Ward Cutler 
139 
As others have noted in the first stage in degeneracy the nucleus increases 
in size and the chromatin aggregates into clumps, Plate VII, figs. 41, 42. In 
some cases these masses are confined to the periphery, but more commonly 
they are found scattered throughout the nucleus. The animal does not increase 
very markedly in size, but large vacuoles often fill the granular cytoplasm. 
When these degenerate organisms are studied in the living condition the 
nucleus is easily seen, the masses of chromatin appearing as retractile bodies; 
this suggests that the chromatin has changed its chemical nature, as was 
noted by Dobell (1909) in degenerate forms of E. ranarum. In E. histolytica 
the amoebae are quite active, but they appear incapable of ingesting food 
substances. 
Nuclear division, of an irregular type, often occurs, so that the animal 
arrives at a condition seen in Plate VII, figs. 43, 44, with six or more degenerate 
nuclei. 
Elmassian in his paper on E. minuta has figured an amoeba, fig. 20, with 
dividing nuclei, which strongly recall the divisions seen in fig. 43. This 
observer did not, however, regard them as degenerate. 
The next stage in degeneracy is the disappearance of the nuclear membrane 
and the passage of the chromatin masses into the cytoplasm, Plate VII, figs. 
45, 46, 53. The production of brown pigment, described in E. ranarum, I have 
not seen. 
Finally enucleate animals are produced, the cytoplasm containing highly 
refractile granules with staining reactions similar to those of chromatin, 
Plate VII, figs. 47, 48. These organisms may live for hours, moving actively 
the whole time. 
Small buds, containing refractile grains, are very commonly produced, 
Plate VII, figs. 49, 50, and correspond with the spores described by Schaudinn. 
In rare cases the nucleus, instead of immediately resolving into chromatin 
masses, becomes uniformly stained. Plate VII, fig. 51, shows two such nuclei 
lying together in a vacuole into which chromatin is being extruded. 
Appearances such as these doubtless led Hartmann to postulate the 
existence of autogamy, where there is fertilization of two reduced nuclei. 
This supposition he has since abandoned. 
Finally the two nuclei undergo further disintegration until a condition is 
reached seen in Plate VII, fig. 52. The end result is for the nuclei to disappear 
completely leaving a few chromatin granules in the cytoplasm. 
Temperature has a decided effect in bringing about degeneration, for if 
a culture, in which the number of these forms is few, be incubated at 22° C. 
instead of at 32-37° C., the great majority of the amoebae pass into this 
condition in a few hours. 
Thermal change cannot, however, be the only operative factor, for cultures 
incubated at the same temperature (32° C.) vary greatly; in some the de¬ 
generate individuals are common, while in others no such forms, or at any rate 
very few, are found. 
