CHAPTER V 



CHARACTERISTICS OF LIVING MATTER 



Amoeba Motion Irritability Assimilation and Metabolic 

 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 definition is still to seek there 

 are certain characteristics of living matter re- 

 cognisable by all, which must now form the 

 subject of our inquiries. 



Suppose we take the case of the unicellular 

 organism known as Amoeba,* a creature some- 

 where about 100 th -inch in diameter and nearly 

 conforming to our notion of the generalised cell, 

 since it consists 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 



* For a fuller account see Hartog, " Protozoa," in Cam- 

 bridge Natural History. 



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