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A First Chapter in Natural History 
NaTuRAL History is the story of all natural objects, plants and 
minerals, as well as animals, though in popular usage it is often confined 
to the last. And while the term animal is very commonly thought to 
refer to mammals only, it being a mistake of frequent occurrence to 
speak of birds and animals when birds and mammals is meant, the 
name animal properly applies to every living or animate creature, from 
the tiny being that can be seen only with the aid of a microscope up to a 
whale, the mightiest creature that has ever lived. 
Broadly speaking, animals are distinguished from plants by their 
ability to feel, move, and digest organic substances such as plants and 
other animals. Plants on the other hand to not feel, have no power of 
voluntary movement, and are nourished by inorganic substances ab- 
sorbed through their roots. The boundary line between animals and 
plants is, however, not sharply defined, especially between the lower, or 
simpler, forms. Some plants move and some animals are rooted to one 
place, and a few plants even have the power to digest animal substances, 
but with all these exceptions the power of voluntary movement remains 
the most evident distinction between animals and plants. 
EVOLUTION 
The smallest and simplest animals consist of an extremely minute 
quantity of a jelly-like substance, termed protoplasm, surrounding a 
central speck of firmer material known as the nucleus. This constitutes 
a cell, and the smallest, simplest animals are formed of a single cell and 
are called unicellular or single-celled animals. The largest of creatures 
is merely a vast assemblage of very.similar cells, grouped into structures 
of different kinds and serving different purposes; and a few naturalists 
have argued that even the very highest animals are really compound 
beings made up of combinations of simple animals. We may, however, 
dismiss this theory as fanciful, while noting that plants, as well as 
animals, are composed of combinations of cells, the cell being the unit 
of life. 
All life is believed to have begun with simple, one-celled beings, be- 
cause the animals we find entombed in the rocks become simpler and 
simpler in structure as we go down. the higher groups of mammals, 
birds, reptiles, etc., disappearing one after the other as we go backwards 
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