PHENOMENA ACCOMPANYING FERTILIZATION 551 



conjugating Infusoria, and the most evident are those in which 

 complete anisogamy occurs. One widely spread effect of such dif- 

 ferentiation is the phenomenon of meiosis or reduction in the number 

 of chromosomes. This also occurs at various periods, furnishing 

 a basis for the categories of conjugant meiosis, gametic meiosis and 

 zygotic meiosis. 



Whatever may be the interpretation of the phenomenon, the fact 

 is obvious that all products of fertilization are labile, active organ- 

 isms quite different in character from the conjugants, hologametes, 

 or gametes which participated in their production. Apparently 

 the same protoplasm, however, is continuous from the old to the 

 young, and during transition certain processes, here described as 

 disorganization and reorganization, have taken place. These pro- 

 cesses, as I believe, are responsible for the renewal of vitality and 

 for the inauguration of a new life cycle in a new organism, evidence 

 for which is given in the following chapter. 



SPECIAL BIBLIOGRAPHY. 



Belar, K.: 1922 1924, LTntersuchungen an Actinophrys sol Ehr, Arch. f. Protis- 

 tenk., vols. 46 (1) and 48. 



Calkins, G. N., and Cull, 8. W. : 1907, The Conjugation of Paramecium caiidatum. 

 Arch. f. Protistenk, voL 10. 



Collin, B.: 1909, La Conjugaison d' Anoplophrya branchiarum St., Arch. zool. exp. 

 et gen. (5), voL 1. 



DoBELL, C, and Jameson, A. P. : 1915, The Chromosome Cycle in Coccidia and 

 Gregarines, Proc. Roy. Soc. B., vol. 89. 



DoGiEL, v.: 1923, The Transformation of a Male Pronucleus into a Spermatozoon, 

 Zool. Lab., Univ. Petrograd. 



Gregory, L. H.: 1923, The Conjugation of Oxytricha fallax, Jour. Morphol., 

 vol. 37. 



Hartmann, M., and Nagler, K.: 1908, Copulation der Ama:ha diploidea, etc., 

 Sitz. ges. Natur. Fr. Berlin, vol. 4. 



Hertwig, R.: 1908, Ueber neue Probleme der Zellenlehre, Arch. Zellforsch., vol. 1. 

 1914, Ueber Parthenogenesis der Infusorien und die Depressionzustande der 

 Protozoen, Biol. CentrllJ., vol. 9. 



Jameson, A. P.: 1920, The Chromosome Cycle of Gregarines with Special Refer- 

 ence to DiplocysHs schneideri, Quart. Jour. Mic. Sci., vol. 64. 



Maupas, E.: 1888-1889, Le rejeunissement karyogamique chez les cilies, Arch, 

 zool. exp. gen. (2), vol. 7. 



Slonimskt, p., and Zweibaum, .1.: 1919, Contributions a I'etude du coloration 

 vitale des Infusoires, Nota Soc. Sci. Varsovia, 1919. 



Zweibaum, J. : 1912, La conjugaison et la difterontiation sexuelle chez les Infusoires, 

 Arch. f. Protistenk, vol. 26. 1921, Richerche sperimentali sulla conjugazione 

 degli Infusori: 1. Influenza della coniugazione sull assorbimento dell, O2 nel Para- 

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