CHAPTER III 



CHARACTERISTICS OF LIVING MATTER AMOEBA 

 MOTIONIRRITABILITYASSIMILATION AND META- 

 BOLIC PROCESSES-RESPIRATION REPRODUCTION- 

 DEATH 



MANY pages could be devoted to a list of the various 

 definitions of life which have been given by different 

 writers, yet none of which has met with full and 

 complete acceptance. But though the final defini- 

 tion is still to seek there are certain characteristics 

 of living matter recognisable by all, which must 

 now form the subject of our inquiries. 



Suppose we take the case of the unicellular Amoeba 

 organism known as amoeba, 1 a creature somewhere 

 about ITO inch in diameter and nearly conforming 

 to our notion of the generalised cell, since it con- 

 sists of an outer coat or ectoplasm, an inner granular 

 protoplasm, a nucleus and a contractile vacuole. 



If we watch this lowly creature we may first of Motion 

 all notice that it moves (see fig. ii.). It does this 

 by pushing out a fragment or projection of its own 



1 For a fuller account see Hartog, " Protozoa," in Cambridge 

 Natural History. 

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