180 O. P. Dellinger. 



the hyaloj^lasm, not by the contraction of the spongioplasm (as con- 

 ceived by Cornoy), that the movements of cells are produced. Of the 

 two substances, the hyaloplasm is the more active, the sj^ongioplasm 

 the more inert. The spongioplasm forms, in fact, a sort of frame- 

 Avork supporting the hyaloplasm and into which, under the influence 

 of stimuli, the hyaloplasm becomes wholly withdrawn" (Schiifer ''On 

 the Structure of Amoeboid Protoplasm," 1891, p. 195). 



Ohjecfluiis to the Coniraction Theory. 



Observations, principally on the movements of the protoplasm in 

 Amoebae ^nd in plant cells, caused many observers to reject the cou- 

 traction theory of the movements of protoplasm. In an advancing 

 Amoeba the supposed currents which gave rise to the objections to 

 contractility as a cause of protoplasmic movement were those begin- 

 ning at the point of advance and extending backward. Wallich (18G3) 

 and Biltschli (1873) for Amoebae, and Hofmeister (1865 and '67) 

 for the plant cell called attention to such currents. Since then many 

 investigators have either thought they observed or else have assumed 

 the presence of surface currents of this kind and have based their 

 theories of protoplasmic movement on them. 



Among those who took this standpoint were Hofmeister (1865 and 

 1867), Biltschli (1873), Quincke (1870 and later), Berthold (1872), 

 and more recently Biltschli (1892), Rhumbler (1898, 1902, '03, '04 

 and '05), Gurwitsch (1901) and many others. 



Unfortunately for the adherents of these theories, the recent inves- 

 tigations of Jennings (1901) and Dellinger (1906) have shown that 

 the backward currents do not exist. It further appears that the real 

 character of the movements in the Amoeba was not at all divined. 



Protoplasm a Complex Fluid. 



Berthold, Quincke, Schwartz, Rhumbler and others. 



Although the doctrine of the fluid nature of protoplasm fell much 

 into discredit during the seventies, it was taken up again in the 

 eighties by a number of investigators. 



Thus, Berthold, in his work published in 1886, came forwa^-d 

 with arguments in favor of this conception which was universally 



