THE LIFE OF THE CELL 111 
CHAPTER XVi 
THE LIFE OF THE CELL 
A PLANT is a living organism and therefore capable of per- 
forming all the functions characteristic of life. It can breathe, 
take in food, respond to its surroundings, reproduce itself, 
just as much as any animal can. In some cases it can even 
move; in fact, it becomes increasingly difficult to say in 
what the difference between a plant and an animal consists, 
for the more the life of plants and animals is studied, the 
greater are their resemblances to each other found to be, 
especially in the lowest forms. At the present time, there 
are organisms which are claimed by both zoologists and 
botanists. 
The properties connected with the presence 
of life are always found associated with a 
substance to which the name protoplasm has been given 
(Gk. plasma=material; protos=first). The very simplest 
organisms, animal as well as vegetable, are merely masses, 
often too minute to be seen without the microscope, of this 
substance. One of the simplest green plants known is 
Protococcus ; it may be obtained from the mud which accumu- 
lates in roof-gutters and water-butts. Very often the water in 
these cisterns looks green or reddish from the millions of 
Protococci it contains. 
Examined under the microscope, it is found that a Proto- 
coccus consists of protoplasm bounded by a transparent 
membrane, the cell-wall. The protoplasm is granular, and 
shows a denser portion, called the nucleus, within which is a 
nucleolus. Confined to certain parts of the protoplasm, not 
evenly distributed through it, is a colouring matter called 
Protoplasm. 
