288 A. FRANKLIN SHULL 



10. Parthenogenesis. Issakowitsch ('07) holds that long-con- 

 tinued parthenogenesis results in an increase of the nucleoplasma 

 ratio in daphnians — a conclusion also reached by Popoff ('07) 

 and Hartmann ('19 a). 



11. Alternating life-cycles. In Cladocera Issakowitsch ('07) 

 infers from degeneration phenomena that the alternating phases 

 of parthenogenesis and sexual reproduction are governed by 

 changes of the Kernplasmarelation^ — a conclusion supported by 

 Popoff ('07), who generalizes from a study of the Protozoa. 

 Papanicolau ('10), after a brief study of intestinal cells in Clado- 

 cera, also concludes that the alternating modes of reproduction 

 are ushered in by changes of the nucleoplasma ratio — a view con- 

 curred in by Hartmann ('19 a). Strohl ('08), however, attacks 

 this view on theoretical grounds, and Woltereck ('11) offers 

 various reasons why the K/P relation can be only secondarily 

 related to the mode of reproduction, if it has anything to do with 

 the cycle at all. 



The above citations are not a complete list, but are probably 

 representative of the types of phenomena which have been held 

 to be explained by, or to cause, changes of relative nuclear volume. 

 They indicate that, among certain biologists, the relative volume 

 of nucleus and cytoplasm is regarded as an important factor in 

 physiology. No further general discussion of the question is 

 contemplated in this paper. Since, however, the observations 

 and experiments here reported bear particularly upon items 10 

 and 11 in the above hst, it is deemed necessary to enlarge upon 

 the application of the Kemplasmarelation theory to partheno- 

 genesis and its alternation with bisexual reproduction. 



RELATIVE NUCLEAR VOLUME IN THE LIFE-CYCLES OF PARTHENO- 



GENETIC ANIMALS 



The first discoveries of the relation of the relative nuclear 

 volume to cyclical phenomena involving a series of generations 

 were made in the Protozoa by Hertwig, Popoff, and others, as 

 related above. Hertwig concludes, from his own studies and 

 those of other workers on Paramecium, Actinosphaerium, Fron- 

 tonia, and Dileptus, that the size of the nucleus increases during 



