172 THE president's address. 



characters to use for purposes of definition and classification, at 

 least at their first origin, since two closely allied organisms may 

 adapt themselves to quite different modes of life. The distinction 

 of animal and plant can only be used for classificatory purposes 

 when, as in the higher organisms, it is so ingrained that the- 

 whole structure of the organism is modified in accordance with it. 



The conclusion from these considerations is that it is no use 

 to attempt to partition the Protista into two primary sub- 

 divisions, animals and plants. We must look for the more funda- 

 mental divergences along some other lines. But at this point 

 I wish to enter a caveat, as the lawyers say, with regard to 

 the logical aspects of the classification of living beings. 



A classification, to be logically perfect, should divide the objects- 

 dealt with into groups of greater or less extent which are defined 

 and distinguished from one another by precise characters verbally 

 expressed. Such a procedure presents no great difficulties, as a 

 rule, in dealing with inanimate objects, because their characters 

 are stable and stationary. Take for instance any common 

 chemical substance, such as carbonate of lime, or silica. There 

 is no reason to suppose that the characters and properties of 

 these substances have changed, or will change, in any finite 

 period of time, however great. It is quite otherwise with living 

 things ; they have undergone, and are undergoing, continual 

 processes of evolution and modification. If w^e could project 

 our vision back to Silurian times, we should see scarcely a single 

 living organism similar to those existing at present ; and who 

 can imagine dimly what will be the state of things in a future- 

 as far distant as the present is from the Silurian epoch ? Possibly 

 the earth may then be inhabited by one single species of 

 organism, the final j)i"oduct of the evolution of man, who will 

 by then have accomplished his apparent destiny of extirpating 

 all other forms of life, and who will obtain the proteids necessary 

 for his sustenance by the aid of chlorophyll manufactured arti- 

 ficially by the ton, and will supply all his wants by means of 

 appropriate mechanical devices. Let us be thankful that we 

 shall none of us live to see that day. 



The continual process of change which living things undergo 

 puts many obstacles in the way of strictly logical classification. 

 In the first place, between any two forms of life, however far apart 

 in the scale, intermediate forms must exist or must have existed.. 



