140 QUARTERLY CHRONICLE. 
a rotatory streaming motion. The movements of the other 
constituents of the mantle-layer (the viscid substances, nu- 
cleus, chlorophyl, and other small corpuscles, and micro- 
scopic crystals) are induced by the mechanical action of the 
rotating mantle-fluid upon them, with the co-operation of 
adhesion and, in the case of the viscid substance, of cohesion. 
The molecular movements of very small chlorophyl and other 
corpuscles visible under favorable circumstances, remain 
excepted therefrom. 
7. The rotatory movement of the mantle-fluid, as also its 
direction, is recognised especially from the constituents of 
the mantle-layer which float freely in it and are set in motion 
by it, namely, the freely moving chlorophyl and other solid 
corpuscles, and this both in the cells with rotation and in 
those with a so-called circulation. In the Chare and in 
Hydrocharis morsus rane the viscid substance is also set in 
motion in separated fragments, in the Chare in a globular 
form, and the current is then called “ rotation.” 
8. The rapidity of movement of the freely floating and 
rotating substances under otherwise similar circumstances is 
secondarily dependent upon their mass, as also upon the in- 
fluences of adhesion, which make themselves felt at the limit 
of the cell-juice, and still more strikingly at the cellulose 
capsule, and during the mutual contact of the floating consti- 
tuents. 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 movements. 
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 neighbourhood of the nucleus or in some 
other favorable spot (Hydrocharis, Uriica urens, Trades- 
cantia, &c.). These changes of appearance resemble in exter- 
nal aspect the motory forms of contractile tissues ; they are, 
however, caused by the quite unavoidable action of the rotat- 
ing mantle-fluid upon the viscid substance, are often demon- 
strably 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 diffused upon 
and adhering to the cellulose capsule in the vicinity of the 
nucleus or in any other spot, when in a favorably tenacious 
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