250 THE MICROSCOPICAL NEWS. 
thickly covered with these cilia which all wave in unison, like a 
field of wheat blown by the wind. This movement propels the 
animal through the water, and produces currents which bring it 
food. These movements, the amoeboid, the streaming, and the 
ciliary, have their exact analogues in the movements of the proto- 
plasm of plants. The Amoeba has been always classed as 
animal, by reason of its deriving nutriment from ready-made proto- 
plasm, but as its whole life history is not yet known, it is by no 
means certain that some, if not all amceba-like organisms may be 
the rudimentary forms or free cell contents of some of the lower 
plants. A fungus is found growing on the surface of tan-pits, 
which, at one period of its existence disintegrates, and the proto- 
plasm of each of its component cells becomes a free organism, 
gliding over the tan in the pit by means of its pseudopodia, and 
exhibiting all the characteristics of an ordinary free amoeba. Here 
then is an analogue of the amceboid movement. The streaming 
movement is exhibited by the protoplasm of the cells of the water 
plant Valisneria, which Mr. Carpenter said had been shown by Dr. 
Gooch at almost all the soirées of the society. In this plant the 
protoplasm does not fill the cells, but only lines them, and is in 
continual motion, streaming up one side of the cell, and down the 
other. The ciliary motion of the protoplasm of plants is typically 
shown in the little unicellular plant, known as Protococcus, the 
presence of which is the cause of the green colour of the water in 
gutters, &c. This plant consists of an oval cell, from one end of 
which two long cilia project, and the lashing movements of these 
cilia propel the creature through the water. ‘The ciliary action is 
not confined to the lower forms of life; the gills of the bivalve 
mollusca, being thickly covered with cilia, the motion of which 
causes a continuous current of water to pass over the gills. Even 
the Vertebrata, including man, have certain organs covered with 
ciliated epithelium. 
All the forms of protoplasm do not exhibit a continuous motion. 
Some require a stimulus, either by heat, a slight electric shock, or 
otherwise, to which they respond by movement. For instance, 
when an amoeba comes in contact with a foreign body smaller 
than itself it immediately responds to the touch by closing round 
it. In plants this irritability is well exemplified by the action of 
the sun-dew. When certain hairs on the leaf of this plant are 
touched it immediately responds by the leaf folding in half along 
the midrib. Protoplasm, therefore, is said to be irritable. Another 
property of protoplasm is the power of taking in external matter, 
and the capacity of converting that matter into its own body- 
substance. Protoplasm is said, therefore, to be receptive and 
assimilative, and it is the possession of these functions which forms 
the great distinction between living and non-living matter. Lastly, 
