442 Gary N. Calkins. 



them are shorter than the normal. Owing to the inner changes 

 the whole organism may at this time be so modified that it is 

 unrecognizable." 



"Thus during the continued inanition of the body, first one part 

 and then another becomes absorbed, first the endoplasm, next the 

 ectoplasm, the trichocysts and the cilia in part, all to maintain as 

 long as is possible the vital functions. In the meantime, however, 

 the nucleus has not escaped without changes as follows:" (loc. 

 cit., p. 98) . . . "In the inside of the macronucleus a 

 rounded mulberry-like mass is developed. Its alveolar structure 

 has changed at the same time, and in the center there are usually 

 one or two small central bodies (Binnenkorper). The high 

 pressure which is developed in the decreasing body form and due 

 to the enlarging vacuoles, causes the nucleus to become greatly 

 deformed and compressed. The various parts of the nucleus are 

 broken up into fragments which may probably be used more or 

 less as food ( t). Of the former large macronucleus there is now 

 left unchanged only the nuclear body which has been formed and 

 this lies between the broken down nuclear parts." (Id., p. 112.) 

 "In the micronucleus no destructive changes are mani- 

 fested during the hunger degeneration. It is the one part of the 

 body which is apparently not affected by the conditions of the 

 experiments, a not unnatural result considering the importance 

 which this organ of these cells has in rebuilding the macronucleus 

 after conjugation. Of all organoids the micronucleus would thus 

 seem to be the most important of the cell." (Id., p. 114.) 



These careful observations and clear results of Wallengren, 

 most of which I have been able to verify, offer a good basis for the 

 comparison of structures obtained in the different stages of the 

 life history of Paramcectum {cf. Figs. 22 and 23). We may 

 distinguish two types of degeneration changes in the series from 

 the start to the finish. One set accompanies starvation, and was 

 characteristic of the first two periods of depression, the other 

 accompanies physiological depression of a different type at the 

 last two periods. In the former the changes in structure had to 

 do mainly with vacuolization of the endoplasm and rupture of the 

 macronucleus, while in the latter the endoplasmic portions were 



