548 THE BEGINNINGS OF LIFE. 



is, indeed, now looked upon as a well-nigh exploded 

 notion as one which, whilst favoured by no valid 

 evidence whatsoever, is absolutely opposed to much 

 general and special knowledge of the highest worth l . 

 Doctrines of Evolution are, therefore, becoming more 

 and more popular amongst biologists, and the mutability 

 of species is now very generally proclaimed. 



If, then, the old word c species' is to be retained, 

 its connotation of immutability must be understood 

 to have been lopped off; so that c ability to repro- 

 duce their like through successive generations' would 

 remain as the distinguishing characteristic of those 

 assemblages of similar individuals which are usually 

 grouped under the word 'species.' The term would 

 seem, then, to be applicable to any assemblage of 

 living things, the members of which were capable, 

 through many generations, of giving rise to other 

 similar forms by a process of reproduction. 



But, it may be asked, is it or is it not of conse- 

 quence how this process of multiplication is brought 

 about ? Processes of fission or of gemmation, variously 

 combined, constitute the sole modes of reproduction 

 occurring amongst all that vast assemblage of organic 

 forms which were provisionally included by Professor 

 Haeckel in the kingdom Protista. Amongst the vegetal 

 forms, it is true, processes of c conjugation ' are also met 

 with representing the first dawnings of the more com- 



1 For an excellent summary of the evidence on this subject, see Mr. 

 Herbert Spencer's 'Principles of Biology,' vol. i. pp. 333-364. 



