(iS) 8 ? 



for any reason or for any necessity that lies in the nature 

 of the case, but simply for the habit of the thing has 

 not yet put himself at home with the metaphysical cate- 

 gories of substance and casualty ; thanks, perhaps, to 

 those guides of .his whom we, the amusing Britons that 

 we are, bravely proclaim " the foremost thinkers of the 

 day" J 



The matter and manner of the whole essay are now 

 fairly before us, and I think that, with the approbation 

 of the reader, its procedure, generally, may be described 

 as an attempt to establish, not by any complete and 

 systematic induction, but by a variety of partial and 

 illustrative assertions, two propositions. Of these 

 propositions the first is, That all animal and vegetable 

 organisms are essentially alike in power, in form, and 

 in substance ; and the second, That all vital and intel- 

 lectual functions are the properties of the molecular 

 disposition and changes of the material basis (proto- 

 plasm) of which the various animals and vegetables 

 consist. In both propositions, the agent of proof is 

 this same alleged material basis of life, or protoplasm. 

 For the first of them, all animal and vegetable organ- 

 isms shall be identified in protoplasm ; and for the sec- 

 ond, a simple chemical analogy shall assign intellect 

 and vitality to the molecular constituents of the proto- 

 plasm, in connection with which they are at least ex- 

 hibited. 



In order, then, to obtain a footing on the ground 

 offered us, the first question we naturally put is, What 

 is Protoplasm ? And an answer to this question can be 

 obtained only by a reference to the historical progress 

 of the physiological cell theory. 



That theory may be said to have wholly grown up 



