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 movement ; — 

 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 life. 

 (3) Those movements are distinguished as Circulation where 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 c-f 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 movements 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, which 

 are apparent from the movement 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, Characeae, Vallisnen'a, 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 power 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 nitric 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 Floridea; and the flowers of Compositge. 



