834 SPONTANEOUS MOVEMENTS IN PLANTS. 
between these lowest forms of animals and the protoplasmic 
elements in the constitution of more highly organised forms. 
If the Amoeba and Gromia are admitted to be distinct indi¬ 
vidual animals, the same line of reasoniug would almost com¬ 
pel us to admit to the same rank the white corpuscles of the 
blood of mammalia, which present almost the same characters 
and possess the same power of protrusion and retractation of 
a portion of their substance. 
The instances above cited illustrate the faculty of spon¬ 
taneous motion possessed by detached portions of protoplasm 
endowed with the power of forming themselves into new indi¬ 
viduals. This phenomenon appears, however, to be but a 
form of the property possessed by all protoplasm of constant 
motion in some form or other. The circulation of the proto¬ 
plasmic mucous fluid within the cells of plants is one of the 
most beautiful phenomena of vegetable life revealed by the 
microscope, and one of which the explanations at present 
offered appear quite inadequate. A favourite object for ex¬ 
hibiting this circulation or rotation is formed by the jointed 
hairs which cover the stamens of the Virginian Spider-wort 
(Tradescantia virginica). The movement is rendered visible 
by the presence in the otherwise colourless fluid of minute 
opaque granules of chlorophyll or other colouring matter; and 
is observable w r ith great ease in the semi-transparent tissue of 
certain water-plants, as Chara, or the Valisneria commonly 
grown in fresh-water aquariums. It consists of a slow move¬ 
ment of the protoplasmic fluid up one side of the cell, across 
the ends, and down the other side ; not perpendicularly, but 
in an oblique or spiral course. The subject has been care¬ 
fully investigated by three French physiologists, MM. Pril- 
lieux, Roze, and Brongniart, who find that the rotation is 
directly influenced in a remarkable manner by the presence 
of light. M. Prillieux kept a moss in the dark for several 
days, when the cells presented the appearance of a green 
network, between the meshes of which was a clear trans¬ 
parent ground. All the grains of chlorophyll were applied 
to the walls which separate the cells from one another; there 
were none on the upper or under w 7 alls which form the sur¬ 
faces of the leaf. Under the influence of light, the grains, 
together with the thin mucous plasma in which they are 
imbedded, change their position from the lateral to the super¬ 
ficial walls, this change taking place, under favorable circum¬ 
stances, in about a quarter of an hour. On attaining their 
new position, the grains do not remain absolutely immovable, 
but continually approach and recede from one another; and 
if again darkened, they leave their new position, and return 
