52 PROTOPLASM OF PROTOZOA 



microdissection apparatus has proved to be a useful instrument in a 

 study of the structure of Protozoa. By use of this method, Kite (1913) 

 determined the ectoplasm of A. proteus to have a moderately high 

 viscosity and cohesiveness. The substance forming the wall of the 

 contractile vacuole seemed to possess a much higher viscosity than the 

 surrounding endoplasm. The nucleus seemed to behave as a highly 

 rigid granular gel. Kite further observed that the protoplasm of Para- 

 mecium was a soft, elastic, and somewhat glutinous gel; the surface 

 seemed to be more viscous than the interior. More recent studies by 

 Chambers (1924); Rowland (1924a, 1924b); Rowland and Pollack 

 (1927); Seifriz (1936), and others on various species of Amoeba 

 have confirmed in a general way the observations of Kite. In addition, 

 C. V. Taylor (1920, 1923) has described the pellicle of Euplotes patella 

 as a firm, fairly tough, rigid substance. The micro- and macronuclei were 

 found to be highly gelatinous, rather rigid structures imbedded in a 

 viscous hyaline matrix. Needham and Needham (1926) in attempting 

 to inject Opalina ranarum made the observation that the outer mem- 

 brane is composed of a thick, tough substance; the inner cytoplasm they 

 found to be jelly-like, so that injected indicators would not spread 

 within it. The suggestion was tentatively made that the failure of the 

 injected indicators to spread within the Opalina might be due to its 

 consistency or to membranes surrounding the numerous nuclei. Follow- 

 ing injection, the organisms continued to swim about, and in a few 

 moments the injected portions suddenly dropped out, often leaving 

 the animals quite riddled with holes. See also Chambers and Reznikoff 

 (1926); Reznikoff (1926), and Morita and Chambers (1929), on in- 

 jection experiments in Amoeba with similar results. 



Reilbrunn (1929b) has used the centrifuge method to study the 

 absolute viscosity of A. dubia, which he found to be approximately 2 

 times that of water at 18° C. Rowever, the viscosity was found to vary, 

 with changes in temperature, from about 2 times water at 18° C. to 

 25 times water at 21/2° C. (1929a). Pekarek (1930), by studying the 

 Brownian movement in Amoeba, has estimated its viscosity to be about 

 6 times that of water. More recently Seifriz (1936), by observing 

 Brownian movement in Amoeba, estimated the viscosity in a quiet form 

 to be 700 to 800 times that of water; in an active form it was much 

 lower. Likewise Pantin (1924b) estimated the absolute viscosity of 



