INTRODUCTION 55 



Hartmann. There is not much to be gained by the substitution of 

 the "energid" theory of Sachs, Strasburger, and Hartmann. If 

 necessan' the conception of the cell should be expanded to permit 

 of the inclusion of all Protozoa with their varied intracellular differ- 

 entiations and with their invariable performance of all of the fun- 

 damental vital activities included in the physiological attributes of 

 higher animals and plants. Each of them is a perfect organism and 

 some of them, in a morphological sense, represent most extreme 

 types of intracellular differentiation, although not in the sense of 

 cell specialization and functional limitation. 



SPECIAL BIBLIOGRAPHY. 



BuTSCHLi, O.: 1882-1889, Protozoa, in Bronn's Thier-Reich, I. 1894, Micro- 

 scopic Forms and Protoplasm (translation bv E. A. Minchin), London, A. and 

 C. Black. 



Delage, Y., and Herouard, E.: 1896, Traite de Zoologie Concrete, I, Paris, 

 Schleicher Freres. 



Dobell, Clifford: 1911, The Principles of Protistology, Arch. Prot., vol. 23. 



Doflein, F.: 1916, Lehrhuch der Protozoenkunde, 4th ed., Jena, Gustav Fischer. 



Faure Fremiet E.; 1907, Mitochondrics et spheroplastes chez les infusoires cilies, 

 Compt. rend. Soc. de biol., vol. 62. 



Hegner, R. W., and Taliaferro, W. H.: 1924, Human Protozoology, New York. 



Lang, A.: 1901, Textbook of Zoologj', Part I, Protozoa. 



Meyer, A. : 1904, Orientirende Untersiichungen iiber Verbreitung, Morphologic 

 und Chemie des Volutins, Botan. Ztg., vol. 62. 



Minchin, E. A.: 1912, An Introduction to the Study of the Protozoa, London, 

 Edwin Arnold. 



P-\scHER, A., and Lemmermann, E.: 1913, Die Siisswasserflora Deutschlands, 

 Osterreichs und der Schweiz, Jena, Gustav Fischer. 



Whitman, C. O.: 1893, The Inadequacy of the Cell Theory of Development, 

 Woods Hole Lectures, Jour. MorphoL, vol. 8. 



Wilson, E. B.: 1925, The Cell in Development and Heredity, New York, Mac- 

 miUan Company. 



