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ANIMAL ACTIVITIES. 
special organs for seeing, hearing, smelling, tasting, 
and feeling. By these organs we discover the world 
about us. Many animals have not these organs of 
sense. Many, indeed, have no organs of any kind, 
yet all animals seem to possess, to some extent, the 
ability to discover their surroundings. If no other 
sense be present, something like our sense of feeling 
seems to be always active. 
We may summarize the most important activities of 
animals as follows: 
(a) Taking food and oxygen. 
( b) Nutrition. 
(c) Excretion. 
( d) Reproduction. 
(e) Movement. 
(f) Discovery. 
Respiration combines in most animals the two im¬ 
portant functions of taking oxygen and excreting waste 
matter. 
Physiology and Anatomy. In studying animals 
we wish most of all to know their activities. But in 
order to understand these activities one must know 
certain facts about the structure of the animals to be 
studied. A sewing-machine has only one activity or 
function, but one must know the form and position of 
many parts before one knows just how the sewing is 
done. When we speak of the six activities mentioned 
we are dealing with Physiology. When we study the 
parts of an organism to learn their positions and shapes 
we are dealing with Anatomy. Evidently, then, anat¬ 
omy and physiology must be studied together in the 
science of Zoology. We do not study anatomy in 
order to become familiar with many new names, but in 
order to understand the activities or uses of the parts. 
