The Scope of Natural Selection. 



Continued from page 129. 



By J. Lionel Tayler. 



The Primitive Characteristics of Protoplasm. 



In this section I wish to briefly recapitulate a few well-known 

 facts and generalisations, which appear to me to lead to the 

 conclusion that natural selection acting on variations has been the 

 sole means of producing divergence and evolution in the organic 

 world, that protoplasm is never really modifiable, although it may be 

 and has been adapted to a marvellous degree. 



In the evolution of organisms certain generalisations have been 

 shown to be in the main true. From the lower to the higher forms 

 organisation tends to grow more complex and also more specialised ; 

 this development consists in a qualitative and a quantitative change. 

 In estimating the value of any theory which claims to be able to 

 largely explain the process of evolution this quantitative, as well as 

 the qualitative, change must be kept in mind. If a study of the 

 lower forms of life leads to the conclusion that even here elimination 

 brings about adaptation, and that there is little or no evidence for 

 modification of structure, while when we compare the higher and 

 lower forms we find that the differences are very largely due to an 

 increase in complexity, and that the qualitative difference is merely a 

 further development or accentuation in the more advanced organism of 

 a property which is always present in the less advanced, then it will 

 be evident that the facts are largely in favour of a purely selectionist 

 theory of evolution. That a study of the facts does lead to such a 

 conclusion I shall now endeavour to demonstrate. 



In the lowest forms of life we are confronted with a kind of sub- 

 stance (protoplasm) which manifests certain peculiarities which 

 appear at first to sharply distinguish it from inorganic material. 

 Protoplasm from its commencement, as far as we are able to examine 

 it, appears to exist in two more or less distinct forms ; these forms are 

 not sharply marked off, but more or less shade into each other, but 

 still are sufficiently clear and distinct to have led apparently to widely 



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