136 HUMBLE CREATURES. 



the lowest known forms of animal life^ distinguished 

 as the " Protozoa" that many of them are even now 

 handied about by naturalists from one kingdom to 

 another ; and it will probably be a long time (if it 

 should ever be) before a clear line of demarcation is 

 drawn between the two realms of animal and vege- 

 table existence. 



For our purpose^ however^ it will suf&ce to state^ 

 thatj in all probability, these primitive types of life, 

 whether animal or vegetable, perform their various 

 movements, imbibe nourishment, grow, and repro- 

 duce, without any appreciable psychical or mental 

 properties, and that their motions are due alone to 

 the contractility of their tissues. Here, therefore, al- 

 though we have life, movement, growth, and repro- 

 duction, we have no animating power that can with 

 propriety be called " mind." 



And now, before enteruig the arena of true animal 

 existence, and endeavouring to trace in outline the 

 progressive stages of mind in the various races of 

 sentient beings, we must repeat a statement made in 

 the first of these treatises on Humble Creatures*, 

 where, in speaking of the principles upon which the 

 modern classification of animals is based, we observed 

 that " each great division of the Animal Kingdom ex- 

 hibits a progressive development in the organization 

 of the various groups that it contains ; and also that, 

 in following the life-history of a single individual in 

 each section, a remarkable analogy is apparent be- 

 * ' Earthworm and Housefly,' p. 27. 



