290 



LOCOMOTORY AND PROTOPLASMIC MOVEMENTS 



causes to-and-fro movements in mass of the protoplasm. Ternetz l has also shown 

 that similar passive movements are produced in the filaments olAscobohu (Ascophanus) 

 carneus by the expansion and contraction of the vacuoles. Streaming movements 

 may also be produced by pressure, and physical streaming of this kind is only 

 secondarily dependent upon vital activity, whereas true circulatory streaming and 

 rotation appear to be directly connected with the latter. There is, however, naturally 

 more than one way in which streaming could be produced by vital activity 2 . 



Engelmann considered streaming to be due to changes of shape in his hypo- 

 thetical inotagmas 3 , while Hofmeister 4 and also Sachs 5 suggested that progressive 

 changes of imbibition passing round the cell by causing the protoplasmic particles 

 alternately to absorb and extrude water would cause them to move in a definite 

 direction. This would, however, involve a movement of the water in the protoplasm 



in the opposite direction, and as a matter of fact this 

 does not take place 6 . Similarly the supposition of Briicke, 

 Hanstein,and Heidenhain that the movement is produced 

 by the contractile activity of a system of tubes or 

 fibrillar network hardly harmonizes with the fact that 

 the whole of the endoplasm is in motion 7 . A forward 

 movement might be produced by an oblique ejection 

 or exudation of water, but if this took place internally 

 it would involve a movement of the cell-sap in the 

 opposite direction, while it could not take place externally 

 in cuticularized hairs exhibiting streaming. 



Amici 8 concluded that the chloroplastids electrically 

 propelled the endoplasm, and a similar conclusion was 

 made by Dutrocnet and Becquerel 9 . Velten 10 also con- 

 sidered that the movement had a direct electrical origin, 

 and was able to produce a circulation of dead floating 

 particles in a cell which was reversed on reversing the 

 FIG. 50. Sectional diagram of direction of the stronp- electrical currents used. The same 



electro - magnetic streaming. The 



small arrows show the direction of occurs when mercury placed over a strong electro-magnet 



the electrical current and the large 



ones the movement of the mercury. is traversed by an electrical current, so that presumably 



the cell-wall is capable of acting as a magnetic mem- 

 brane n . (Fig. 50.) Such action involves a corresponding backward reaction upon 



1 Ternetz, Jahrb. f. wiss. Bot, 1900, Bd. xxxv, p. 273. 



2 See the literature quoted by Butschli, Unters. iiber mikr. Schaume, 1892, p. 173. 



3 Engelmann, 1. c., p. 373. * Hofmeister, Pflanzenzelle, p. 63. 



5 Sachs, Physiologie, 1865, P- 45 J - 



6 Cf. Ewart, Protoplasmic Streaming in Plants, pp. 109, no. 



7 Briicke, Unters. iiber das Protoplasma und die Contractilitat ; Sitzungsb. d. Wien. Akad., 

 1862, Bd. XLVI, Abth. ii, p. 36; Hanstein, Protoplasma, Heidelberg, 1880; Heidenhain, Einiges 

 iiber die sog. Protoplasmastromungen, 1897 (reprint from Sitzungsb. d. physik.-medic. Ges. zu Wiirz- 

 burg). Cf. Ewart, L c., p. 108. * Cf. Dutrochet, Ann. d. sci. nat., 1838, 2 e ser., T. IX, p. 78. 



9 Dutrochet and Becquerel, 1. c., pp. 85-7. 



10 Velten, Bot. Ztg., 1872, p. 147; Flora, 1873, p. 82; Sitzungsb. d. Wien. Akad., 1875, 

 Bd. LXXIII, Abth. i, p. 343. 



11 On the paramagnetism of cellulose cf. Ewart, I.e., 1903, p. 47. 



