PROTOPLASM 9 



Organization includes form, size, organs or parts, as well as 

 minute structure and chemical composition. While no two 

 organisms are of exactly the same form, there are certain fea- 

 tures that are very common. Living bodies are usually bounded 

 by curved surfaces. They tend to be elongated in one axis 

 more than in others; they tend to repeat certain of their parts; 

 and they incline to be symmetrical. They are limited in size, — 

 although some are very small and some are very large. They 

 are differentiated, — that is, they have organs, different kinds of 

 structures at different parts of the body. As we shall see later 

 they are made up of a substance called protoplasm, which is 

 arranged in one or more cells. 



Among the powers and activities of a living object may be 

 mentioned (i) the power of changing food into its own substance, 

 and thus of growth and repair; (2) the power of using this 

 growth to separate off a portion and thus make a new individual 

 like itself (reproduction); (3) the power to use some of the 

 material of growth to develop energy of motion, heat, light, 

 electricity, or thought, as the case may be; and (4) the ability 

 by means of sensitiveness and the use of these various powers 

 to adjust itself to very considerable changes in the environment. 

 Every organism has all these qualities in some measure. No 

 inorganic object has them. 



15. The Relation of Protoplasm to Life. — Whatever life 

 may be, in the last analysis, we never observe its manifestations 

 except in connection with a substance called protoplasm, which 

 is found both in plants and animals. Protoplasm does not con- 

 tain any chemical elements which are not found in other than 

 living materials. Notwithstanding this fact, protoplasm is 

 different from any other known substance. It is more com- 

 plex and more highly organized, as to its machinery, than any 

 other chemical or physical compound whatsoever. Protoplasm 

 has the power of growing by taking into itself and changing 

 non-living substances; but, so far as we know, it is never pro- 

 duced except as the result of the growth and division of 

 antecedent protoplasm. The protoplasmic or living material 

 in an organism is normally composed of a number of unit- 



