DR. DUFFIN, ON PROTOPLASM. 259 
to a repetition of what has been already stated. The follow- 
ing experiment will show how sensitive the protoplasm is to 
certain reagents :—The staminal hairs of Tradescantia Vir- 
ginica, just prior to complete development, contain many 
small starch granules in their protoplasm; these become 
violet blue on the addition of iodine. If, whilst the move- 
ment is active, a little extremely dilute, iodine solution be 
added, all activity of the protoplasm will rapidly be arrested, 
even before the starch granules give any indication of a blue 
colour, or the protoplasm or cell-wall change their tint. In 
exposing these cells to the electrical current, it is found that 
about the same force of stream is requisite to arrest the move- 
ment of the granules as was noted for the pseudopodia. 
Curiously enough, those hair-cells through whose long axis 
the current was passed, died more rapidly than those whose 
long axis lay at right angles to it. The influence of the 
current on the movement of the granules was restricted to 
a retardation of it which precedes incipient decomposition. 
This must, of course, not be confounded with the changes in 
the arrangement of the protoplasm as described by Briicke,* 
when speaking of the hairs of Urtica urens :—“To follow the 
influence of the electric stream in its separate stages it is 
best at first to close the circuit only for one or two seconds, 
so that the hair only receives a short series of shocks. The 
earliest change which is then observed generally consists in 
the appearance of a greater or less mass of threads which 
project from the body of the cell into the intracellular fluid. 
. .« Occasionally they shoot forth like rockets from the 
body of the cell, as soon as the circuit of the magneto-elec- 
tromoter is closed. . . At their extr emity they often bear 
a greater or smaller intumescence, and they are engaged in 
a constant tremulous or oscillating movement of varying 
intensity.” 
Both Heidenheim and Schultze have seen the threads of 
Tradescantia become varicose under the influence of the 
electric current. A temperature of 30°—40° C. increased 
the rapidity of the granular movement, and it was found that 
the velocity of that in the pseudopodia of the Milolides 
precisely coincided with the highest obtained from the pro- 
toplasm of vegetable cells. The temperature which was fatal 
to Tradescantia, Urtica urens and Vallisneria spiralis, proved 
to be 48° C. Already at 38° C., however, the movements 
began to slacken. 
The difficulty of bringing the movements of the granules 
* “Das Verhalten d. sogenannten Protoplasmastréme in der Brenuhaaren 
von Urtica Urens,” etc., ‘ Kais. Akad. d. Wiss.,’ Bd. xlvi, June 20, 1862. 
VOL. III.—NEW SER. Tv 
