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merits, whose constant change is the physical basis of what 

 we understand as life. It has received the name of Proto- 

 plasm. We know that Protoplasm in the mass does not 

 act as the living material, but that it consists of minute 

 bodies each of which acts as an independent living being. 

 Unfortunately the name cell got to be extended to these 

 bodies, which are not like cells at all. It is better to call 

 them Protoplasts. All plants and animals are built up 

 by these protoplasts. These little beings are like workmen 

 who build a house, the cell -wall is the structure built 

 mainly of a substance called cellulose, the contained living 

 being is the builder, and he builds to an inherited plan. 

 A protoplast is not a simple mass of protoplasm, but 

 consists of definite parts. There is a nucleus which 

 appears to exercise control, also many more or less specially 

 shaped bodies which do work in constructing material, 

 some are green, others coloured or colourless. They all have 

 their duties, and they, together with the nucleus, are 

 embedded in a portion of protoplasm which is given the 

 special name of Cytoplasm. 



