XI PHENOMENA OF ORGANIC NATURE 305 



in question has satisfied those conditions, how far 

 he has not satisfied them, how far they are satis- 

 fiable by man, and how far they are not satisfiable 

 by man. 



To-night, in taking up the first part of the 

 question, I shall endeavour to put before you a 

 sort of broad notion of our knowledge of the con- 

 dition of the living world. There are many ways 

 of doing this. I might deal with it pictorially and 

 graphically. Following the example of Humboldt 

 in his " Aspects of Nature," I might endeavour to 

 point out the infinite variety of organic life in 

 every mode of its existence, with reference to the 

 variations of climate and the like ; and such an 

 attempt would be fraught with interest to us ail ; 

 but considering the subject before us, such a course 

 would not be that best calculated to assist us. In 

 an argument of this kind we must go further and 

 dig deeper into the matter ; we must endeavour to 

 look into the foundations of living Nature, if I 

 may so say, and discover the principles involved in 

 some of her most secret operations. I propose, 

 therefore, in the first place, to take some ordinary 

 animal with which you are all familiar, and, by 

 easily comprehensible and obvious examples drawn 

 from it, to show what are the kind of problems 

 which living beings in general lay before us; and 

 J shall then show you that the same problems are 

 laid open to us by all kinds of living beings. 

 But first, let me say in what sense I have used the 



