QUARTERLY CHRONICLE. 139 
men, but not well known as regards its other chemical 
properties ; with respect to the circulation, it is the motionless, 
resting part of the cell-contents. 
3. To the “ mantle-layer”’ belong the following consti- 
tuents :—The ‘‘ mantle-fluid ” as I have called it; the tena- 
ciously fluid substance named “ protoplasm” by Hugo Mohl; 
chlorophyl corpuscles, and other very small solid corpuscles, 
the chemical nature of which cannot be ascertained posi- 
tively ; the cell-nucleus; microscopic crystals ; and the pri- 
mordial utricle when this is present, which would form the 
boundary of the “mantle-layer’’ towards the cellulose 
capsule. 
4, In the Characez the “ mantle-fluid” cannot be over- 
looked ; it was, however, erroneously assimilated to the tena- 
cious fluid substance of circulating sap-currents, the so-called 
protoplasm-currents, and rightly distinguished only by Nageli. 
In the cells with circulating sap-currents, it was first detected 
by E. Briicke in the stinging-hairs of Urtica urens ; and it 
was observed in all the cells with rotating or circulating sap- 
currents examined by me. It is diffused between the cell-juice 
and the cellulose capsule, or the primordial utricle when this 
is present, is fluid, rich 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 dis- 
solved 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 albu- 
minous, more or less tenacious as regards its state of cohesion, 
and presents 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 tobe found. Among 
the crystals were observed irregularly stellate ones of un- 
known chemical constitution (Hydrocharis morsus rane), and, 
in the stinging-hairs, oxalate of lime. 
6. In the currents of the vegetable cell only the consti- 
tuents 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 exclusively, on the .“‘ mantle-fluid,’” which 
has hitherto remained quite unnoticed ; this is thereby set in 
