414 PROF. TH. W. ENGELMANN. 



frequent formation of at first distinctly hyaline spherical pro- 

 minences into which the granular mass of the interior sub- 

 sequently streams. Here a general contraction of all the 

 inotagmata of the protruding portion of the hyaline exoplasm 

 may be taken as the cause. As the subsequent unhindered 

 streaming of the granules shows, the cohesion within the 

 hyaline process is very slight and does not sensibly differ from 

 that of a fluid. According to the account first given by 

 Ecker ^ for Amoeba, which is the one most widely spread among 

 zoophysiologists, the processes are pushed forward by the con- 

 traction of the protoplasm lying behind them, especially in the 

 superficial layer. Dujardin supposed and De Bary '^ proved, 

 that the cause of the advance of the mass must necessarily be 

 produced in this case at the periphery of the stream. De Bary 

 found the cause in a there (at the periphery) existing '^relaxa- 

 tion or expansion by means of which the granular stream is 

 pulled onwards, either sucked up, just as water is sucked up 

 by a porous body, or simply streaming thither, it being the 

 place of least resistance." Hofmeister also opposed the pre- 

 vailing view most vigorously, especially upon this ground, that 

 the granular streaming spreads backwards from the periphery 

 where the movement, the extrusion of the process, takes place, 

 i. e. the granules nearest the periphery are the first to move 

 towards it, those farther away commence moving subsequently. 

 It has been correctly remarked that no contraction of those 

 portions of the periphery lying on the other side, the side away 

 from which the body is moving, can be observed, contraction 

 which must necessarily express itself in a smooth stretched 

 superficies which is thus diminished in extent. On the con- 

 trary, as may be seen in every amoeboid mass which is quickly 

 advancing, the superficial portion of the hinder region of the 

 body, Avhile its volume is constantly diminishing, is not smooth, 

 but wrinkled, folded, if not actually drawn out into fibres. 

 There is, however, at least according to De Bary,^ a forma- 



' Ecker, 'Ztschr. f. w. Zool.,' i, p. 235, 1849. 



" De Bary, ' Die Mycetozoen,' 2 Aufl., p. 47, et seq., 1864. 



a De Bary, 'Die Mycetozoen/ 2 Aufl., p. 47, 1864. 



