with reference to the question of Contractility* 11 



in water, exhibits only a small amount of albumen, and does not 

 mix with the cell-juice. Its saline contents and the presence of 

 other organic substances dissolved in it cannot be accurately 

 ascertained ; but it may be taken as a matter of course that it is 

 in chemical reciprocal action with the other constituents of the 

 mantle-layer. 



5. The other constituents of the mantle-layer are bathed by 

 the mantle-fluid or suspended in it. Amongst the constant ones, 

 leaving out of consideration the questionable primordial utricle, 

 are the viscid substance and the chlorophyl and other small 

 corpuscles. The "viscid substance" is strongly albuminous, 

 more or less tenacious as regards its state of cohesion, and pre- 

 sents itself in different and variable arrangement and form 

 before and during the flow of the sap. Neither the nucleus nor 

 the microscopic crystals are always to be found. Among the 

 crystals were observed irregularly stellate ones of unknown 

 chemical constitution {Hydrocharis morsus ranee), and^ in the 

 stinging-hairs, oxalate of lime. 



6. In the currents of the vegetable cell only the constituents 

 of the "mantle-layer," not including the primordial utricle, 

 take part. But whatever be the causes or forces by which these 

 phenomena are produced in the constituents of the "mantle- 

 layer, " their action is demonstrably exerted especially, and exclu- 

 sively, on the " mantle-fluid," which has hitherto remained quite 

 unnoticed ; this is thereby set in a rotatory streaming motion. 

 The movements of the other constituents of the mantle-layer 

 (the viscid substance, nucleus, chlorophyl and other small 

 corpuscles, and microscopic crystals) are induced by the mecha- 

 nical action of the rotating mantle-fluid upon them, with the 

 cooperation of adhesion and, in the case of the viscid substance, 

 of cohesion. The molecular movements of very small chloro- 

 phyl and other corpuscles visible under favourable circumstances 

 remain excepted therefrom. 



7. The rotatory movement of the mantle-fluid, as also its 

 direction, is recognized especially from those 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 cor- 

 puscles, and this both in the cells with rotation and in those with 

 a so-called circulation. In the Charce and in Hydrocharis morsus . 

 rarue the viscid substance is also set in motion in separated 

 fragments, in the Charce 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 



