HEALTH AS A HERITAGE 
CHAPTER I 
THE ORIGIN OF PLANT AND ANIMAL CHILDREN 
Little children are still the symbol of eternal marriage between love 
and duty. — George Eliot. 
I. Plants and Lower Animals 
Life from Life. — In this lesson we shall aim to answer the 
question : How do new beings come into existence ? People 
once thought that in fermenting or decaying substances cer¬ 
tain minute living forms came into existence spontaneously; 
that is, that living things were produced just by the process 
of decay. But the microscope has revealed to us the details 
of the life of the tiny beings that exist in decaying things, 
and we now know, thanks to Louis Pasteur, that these lowly 
forms, as well as the plants and animals of more complex 
structure, come from preceding living beings of the same 
kind. Life comes only from life. 
1. What was the doctrine of spontaneous generation? 
2. Who disproved this old error? 
3. What is the antecedent of every living thing? 
Cells. — The living substance of every plant or animal 
resembles the raw white of egg. It is called protoplasm . It 
exists in tiny specks or in sacks. Each speck is a cell, and 
each cell has a central spot, called a nucleus (plural, nuclei). 
The cells, together with the substance which lies between 
them, compose the tissues which make up the bodies of all 
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