ORGANIC EVOLUTION: DARWINIAN AND DE VRIESIAN. 



By N. C. Macnamara, F. R. C. S., 



Fellow of the Royal College of Surgeons of England, and also of the Royal College of 

 Surgeons of Ireland; Fellow of the Calcutta University. 



The term "organic evolution" implies that existing organisms are 

 children of the past and the parents of the future. As biologists we 

 hold that this order of tilings is the result of natural processes of growth 

 and change working throughout past ages; in fact, that existing 

 plants and animals are the lineal descendants of ancestors on the 

 whole somewhat simpler in organization, and that these are derived 

 from still simpler forms, and so backward to pre-Cambrian geo- 

 logical periods, when we have reason to believe that living organic 

 matter first came into existence on the earth. Of one thing we may 

 be sure, which is that evolution, according to the above definition, 

 depends on the fact that the living substance which constitutes the 

 essential part of organisms on the one hand is capable of passing 

 its form and functions on to its descendants, and on the other hand 

 possesses an organic changefulness which we call variability. 1 



Organic evolution implies a definite structural arrangement and 

 combination of an aggregate of elements into a form which constitutes 

 a unit or cell; one or it may be a mass of these units form the body 

 of an organism. This form of matter is known as protoplasm or the 

 basis-substance of life, because the complete series of phenomena 

 which collectively we call life are manifested through the instru- 

 mentality of this kind of matter. 2 



The protoplasm of living cells, among its other constituents, inva- 

 riably contains a chemical compound known as protein, a wonder- 

 fully complex substance. For instance, the protein which exists in our 

 red blood cells is said to be composed of molecules having a chemical 

 formula of C 600 H 960 N 154 Fe0 179 , whereas the formula of water is H 2 0. 

 And just as the peculiar properties. of water are given to it by the 



i Heredity, by J. Arthur Thomson, p. 12, London, J. Murray, 1908. 



2 These phenomena include the power possessed by living protoplasms of replacing its worn-out elements 

 from surrounding materials without changing its form or functions, of reproducing its like, of respiring, 

 and by chemical action of forming enzymes; it is also capable of being modified by external and internal 

 forces in such a way as to become a transformer of energy into psychical and other processes. 



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