508 BIOLOGY OF THE PROTOZOA 



separated, continues with the same (h^ision-rate that it would have 

 had had it not conjugated. Yet the history of isolation cultures 

 with exceptions noted above, shows that ultimately if conjugation 

 and parthenogenesis are continually prevented, the race, like 

 anisogametes, will die. 



This l)rings us to the consideration of the phenomena, including 

 meiosis and reduction of chromosomes taking place during fertiliza- 

 tion, and to the much-discussed matter of the effects of conjugation 

 or fertilization generally on the organization and on vitality. These 

 will be discussed in the following chapters. 



SPECIAL BIBLIOGRAPHY. 



Baitsell, G. a.: 1914, Experiments on the Reproduction of the Hypotrichous 

 Infusoria: (2) A Study of the So-called Life Cycle oi Oxytricha fallax and Pleuro- 

 tricha lanceolata, Jour. Exp. Zool., vol. 16. 



Bklak, K.: 1921, Untersuchungen iiber den Forniwechsel von Actinophrys sol, 

 Biol. Zentralbl., vol.41. 



Calkins, G. N.: 1904, Studies on the Life History of the Protozoa: (4) Death of 

 the A Series, Jour. Exp. Zool., vol. i. 1919, Uroleptus mobilis: (2) Renewal of 

 Vitality Through Conjugation, Ibid., vol. 29. 1921, Uroleptus mobilis: (4) 

 Effect of Cutting During Conjugation, Ibid., vol. 34. 1923, What did Maupas 

 Mean? Am. Nat., No. 57. 



Dawson, J. A.: 1919, An Experimental Study on an Amicronucleate Oxytricha: 

 (1) Study of the Normal Animal with an Account of Cannibalism, Jour. Exp. 

 Zool., vol. 29. 



Enriques, p.: 1916, Duemila cinquento generazione in un infusorio senza con- 

 jugazione ne partenogenesi ne depressioni, Real. Ac. Inst. Bologna. 



Hartmann, M.: 1921, LTntersuchungen liber die Morphologie unci Physiologie 

 des Formwechsels der Phytomonadinen (Volvocalcs) : III. Die dauernd agame 

 Zucht von Eudorina elegans, experimcntelle Beitriigc zum Befruchtungs und 

 Todproblem, Arch. f. Protistenk., vol. 42. 



Jennings, H. S.: 1913, The Effect of Conjugation in Paramecium, Jour. Exp. 

 Zool., vol. 14. 1920, Life and Death, Heredity and Evolution in Unicellular 

 Organisms, Badger, Boston. 



Maupas, E.: 1888, Sur la multiplication des Infusoires cilies. Arch. zool. exp. 

 et. gen. (2) vol. 6. 



Robertson, T. B.: 1921, The Multiplication of Isolated Infusoria: (11) The 

 Influence of Mutual Contiguity upon Reproduction Rate and the Part Played 

 Therein by the "X" Substance etc. Biochem. Jour. vol. 15. 



Woodruff, L. L.: 1905, An Experimental Study of the Life History of Hypo- 

 trichous Infusoria, Jour. Exp. Zool., vol. 2. 1911, The Effect of Excretion 

 Products of Paramecium on its Rate of Reproduction, Jour. Exp. Zool., vol. 10. 

 1921, The Present Status of the Long-continued Pedigree Culture of Paramecium 

 aurelia at Yale University, Proc. Nat. Acad. Sci., vol. 7, No. 4. 



Woodruff, L. L.,.and Erdmann, R.: 1914, A Normal Periodic Reorganization 

 Process Without Cell Fusion in Paramecium, Jour. Exp. Zool., vol. 17. 



Woodruff, L. L., and Spencer, H.: 1924, Studies on Spathidium spathula: II. 

 The Significance of Conjugation, Ibid., vol. 39, No. 2. 



