STRUCTURAL DIFFERENTIATIONS 163 



In Dinoflagellata, according to Schiitt (1892), there are, in addi- 

 tion to the contractile vacuole, large fluid-filled vacuoles which 

 likewise open to the outside at the flagellum fissure by a fine pore 

 canal. These are termed sac-pusules by Schiitt and differ in func- 

 tion apparently from the collecting pusules or contractile ^'acuoles 

 proper. Doflein suggests that these larger vacuoles may perform a 

 h\'drostatic function. The term pusule is applied by Schiitt in 

 view of the presence of distinct membranes and the absence of 

 rhythmical pulsations, features which distinguish them from ordin- 

 ary contractile vacuoles. 



SPECIAL BIBLIOGRAPHY. 



Bheslau, E.: 1921, Die experimentelle Erzeugung von Hiillen bei Infusorien als 



Parallele zur Membranbildung bci der kiinstlichen Parthenogenese, Die Natur- 



wiss., vol. 4. 

 BiJTSCHLi, O.: 1882-1888, Protozoa, Bronn's Tierreich. 

 Doflein, F.: 1916, Lehrbuch der Protozoan, 4th ed., Jena. 

 Hyman, L. H.: 1917, Metabolic Gradients in Ainceha and Their Relation to the 



Mechanism of Ama-boid Movement, Jour. Exper. Zool., vol. 24, No. 1. 

 Maier, H. N.: 1903, Der feinere Ban der Wimperapparate der Infusorien, Arch. 



Prot., vol. 2. 

 Maupas, E.: 1883, Contributions a I'etude morphologique et anatomique des 



Infusoires cilies, Arch. zool. exper. et gen., vol. 1 (2). 

 Rhumbler, L.: 1898, Physikalische Analyze von Lebenserscheinungen der Zelle, 



Arch. f. Entwcklngsmech. vol. 7. 1910, Die verschiedenartigen Nahrungsauf- 



nahmen bei Amoben als Folge verschiedener Colloidal zustiinde ihrer Oberflachen. 



Ibid., vol. 30. 



