28 PHARMACEUTICAL BOTANY 
In order that the oxidation of protoplasm, referred to in the 
preceding paragraph, may take place, a constant supply of 
oxygen is essential. The water in which Amoeba lives contains 
this gas in solution. Now, the protoplasm of the Amoeba (as 
well as other living organisms) is continually forming carbon 
dioxide. When two gases are separated from one another by a 
porous septum, an interchange takes place between them, each 
diffusing into the space occupied by the other. The process of | 
gaseous interchange is precisely what takes place between the 
H2O in the surrounding water and the CO, in the interior of the — 
Ameceba, the protoplasm acting as a porous partition. This 
gaseous interchange whereby this organism takes in oxygen and 
gives carbon dioxide off is called respiration or breathing. ‘The 
oxygen taken in by the Amoeba oxidizes the complex carbon 
compounds within its body with an accompanying release of 
energy. 
In order that the race of Amoeba may not be exterminated, 
there must be some provision whereby its numerous casualties 
may be balanced. In other words, Amoeba must produce new 
individuals like itself. This function is called reproduction. 
Ameeba reproduces itself by the simplest method of reproduc- 
tion, known as simple division or binary fission. At first the nucleus 
divides into two; then the whole organism elongates, the two 
nuclei at the same time traveling away from one another; next a 
furrow appears across the middle of the elongated body between 
the nuclei; the furrow deepens until finally the organism sepa- 
rates into two separate Amoeba, which henceforth lead an 
independent existence. 
- Under unfavorable circumstances, such as the drying up of 
the water in pools in which it exists and the approach of cold 
weather, the Amoeba draws in its pseudopodia, loses most of its 
water content, becomes spherical in shape and develops on its 
outer surface a thick resistant wall called a cyst. Inside of the 
cyst the nucleus undergoes division to form a large number of 
nuclei. Cells walls then appear dividing up the cell contents 
into as many little Amoebas called Amoebulz as there are nuclei. 
Upon the approach of favorable conditions, these Amoebulz 
escape by — of the cyst, cach Alte dome into an active | 
