PROTOPLASM AND NUCLEUS. 
39 
and antherozoids. This is characterised by the naked protoplasm-mass — swarm-cell 
or antherozoid — not changing its external form, while motile vibratile cilia, which 
are probably slender threads of protoplasm, cause rotation round the longer axis, 
and at the same time a progressive motion in the water. (2) Amoehoid jfiovemejil ; — 
consisting of rapid changes in the external shape of naked protoplasmic structures, 
Myxoamoebae and plasmodia, which, while under water or in moist air on a 
firm support, creep about as if flowing, extending, and contracting; while within 
both the principal mass and the appendages which proceed from it a ' streaming ' 
motion occurs. 
(B) Movements of the protoplasm within the cell-wall. These commence 
after the protoplasm- mass of the cell has formed a larger sap cavity, and continue 
commonly after the growth of the cell has ceased until the end of its Hfe. 
(3) Those movements are distinguished as Circidaiion vvhere threads and bands, 
proceeding from the parietal protoplasm, run to that portion which envelopes the 
nucleus, and often stretch completely across the sap-cavity. A distinction is drawn 
between movements of larger portions of protoplasm, and the 'streaming' 
movement of the substance of which they are composed; the former consist in the 
accumulation or diminution of the parietal layer, in movem.cnts in different directions 
of the mass which contains the nucleus, and, dependent on this, in different groupings 
of the threads. Within these structures themselves currents often occur, Mhich 
are apparent from the miovement of the enclosed granules, and are often in 
opposite directions within the same slender thread. In the cells of lower and higher 
plants which contain much protoplasm and sap but only a small quantity of granular 
contents, the circulation is a widely distributed phenomenon, especially visible in 
the hairs. (4) The term Rotation is applied to those cases where the whole 
mass of protoplasm enclosing a cell-cavity circulates as a thick current complete 
in itself, and carries along with it the grains and granules contained in it. This 
occurs in some water-plants, Characeas, Vailisneria, root-hairs of Hydrocharis, &c. 
(a) The protoplasm exists in two conditions, which may be distinguished as the 
living and the dead ; the former passes over into the latter by the most various chemical 
and mechanical processes ; the reactions of living protoplasm towards chemical reagents 
are essentially different from those of dead protoplasm ; but this of course can only 
be perceived when the reagents do not at the same moment cause death. Solutions 
of different colouring matters, as aqueous solutions of the colours of flowers and the 
juices of fruits, especially also weak acetic solution of carmine, have no povi'er of 
colouring living protoplasm ^ ; but if it has been previously killed, or if it has lost 
its vital properties by long-continued action of these reagents, it absorbs a re- 
latively larger quantity of colouring material than of the solvent, and the whole 
substance assumes a much more intense colour than the reagent. Solutions of iodine 
in water, alcohol, potassium iodide, or glycerin, act in a similar manner; they all cause 
a yellow or brown colouring of the protoplasm, which is more intense than that of 
the solution itself. If protoplasm is first treated with nilric acid, the excess of 
acid removed by water, and potash solution added, it assumes a deep yellow colour ; 
saturated with a solution of cupric sulphate and then treated with potash, it becomes 
* In consequence of this the protoplasm and nucleus are colourless even when the sap is coloured 
in living cells; in other cases, on the other hand, the protoplasm is tinged by a colouring matter soluble 
in water which is not present in the cell-sap, as in 1^'loridea.' and the flowers of Compositse. 
