12 Prof. Reichert on the Sap- currents, 



the cell-juice, and still more strikingly at the cellulose capsule 

 and during the mutual contact of the floating constituents. In 

 consequence of the operation of adhesion, it may also happen 

 that the constituents passively carried on become momentarily 

 or more permanently quiescent, or even acquire retrograde move- 

 ments. 



9. The mechanical action of the rotating mantle-fluid reveals 

 itself also by the change of appearance and form of the viscid 

 substance (^^ protoplasm'^), both in its freely swimming state 

 (Hydrocharis) and also especially during its adherence to the 

 cellulose capsule, whether transitory or permanent, in the neigh- 

 bourhood of the nucleus or in some other favourable spot [Hydro- 

 charis, Urtica urens, Tradescantia, &c.). These changes of ap- 

 pearance resemble in external aspect the motory forms of con- 

 tractile tissues ; they are, however, caused by the quite unavoid- 

 able action of the rotating mantle-fluid upon the viscid substance, 

 are often demonstrably combined with a permanent displacement 

 of the mass, and cannot be regarded as the effect of molecular 

 movements of the particles in the substance itself. 



10. It is a matter of course, and will also be established by 

 direct observations, that the viscid substance difi'used upon and 

 adhering to the cellulose capsule in the vicinity of the nucleus 

 or in any other spot, when in a favourably tenacious state of 

 cohesion, will be drawn out by the mechanical action of the 

 rotating mantle- fluid into long filaments or cords, either simple 

 or branched, and either terminating in free extremities or uniting 

 again in circular or elliptical forms, and converted by the co- 

 operation of adhesion into a more or less complicated net 

 difi'used between the cellulose capsule and the cell-juice. This 

 is the arrangement and configuration of the viscid substance in 

 the cells of plants with a so-called circulating or circulo-rotating 

 current; and this is the foundation of the so-called "proto- 

 plasmic currents '^ so often spoken of. When the viscid sub- 

 stance is thus arranged, the free-swimming granules very easily 

 get into the domain of its fibres and cords, and may even dis- 

 appear entirely from the open region of the mantle-fluid, and in 

 the struggle between the influences of the rotating mantle-fluid 

 and of adhesion perform such vacillating and leaping movements 

 as to remind one of the so-called " granular movement " of con- 

 tractile substances. Lastly, in this arrangement the viscid sub- 

 stance may be set in motion in the region of its fibres and cords, 

 as is proved by the progression on the fibres of swellings with 

 imbedded granules or crystals ; but the tenacity of the substance 

 may be so considerable, and the power of the rotating fluid so 

 small, that such a movement either does not take place at all, 

 or not through the whole extent of the net (E. Briicke) . 



