82 SECTIONAL ADDRESSES, 



of these difficulties culminated when I discovered, covering the bottom 

 of my stock bottle of distilled water — water which had been carefully 

 redistilled from bichromate of potash and sulphuric acid in all-glass 

 apparatus — a healthy growth of mould. 



Let us then assume that we are allowed to postulate in primitive 

 sea-water or other natural water organic compounds formed by the 

 energy of light vibrations from ions present in the water, and see how 

 we may proceed to picture the building up of elementary organisms. 

 Without doubt the evolutionary step is a long and elaborate one, for 

 even the simplest living organism is already highly complex both in 

 structure and function. As the molecules grew more complex by the 

 progressive linkage of the carbon atoms of newly formed carbohydrate 

 and nitrogenous groups, we must suppose that the organic substance, 

 for purely physical reasons, assumed the colloidal state, and at the same 

 time its surface-tension became somewhat different from that of the 

 surrounding water. With the assumption of the colloidal state, the 

 electric charges on the colloidal particles would produce the effect of 

 adsorption and fresh ions would be attracted from the surrounding 

 medium, producing a kind of growth entirely physical in character. 

 We thus arrive at the conception of a mass of colloidal plasma differing 

 in surface-tension from the water and increasing in size by two pro- 

 cesses, the one chemical, due to linkage of carbon atoms ; the other 

 physical, brought about by the adsorption of ions by the colloidal 

 particles. 



The difference of surface-tension would tend to make the surface a 

 minimum and the shape of tlie mass spherical. On the other liand, 

 maximum growth would demand maximum exchange with the sur- 

 rounding medium, and hence maximimi surface. From the antagonism 

 of these two factors, surface-tension and growth, there would follow, 

 firstly, the breaking up of the mass into minute particles upon the 

 slightest agitation, and, secondly, changes of form wherever growth 

 involved local alterations of surface-tension, which changes of form 

 would represent the first indication of the property of contractility. 



So far we have considered only the process of the building up of 

 the elementary plasmic particles, the anabolic process. Church, whose 

 memoir already referred to I am now closely following, points out that 

 these anabolic operations must from the beginning have been subject 

 to the alternations of day and night, for during the night the supply of 

 external energy is removed. 'If during the night,' he asks, 'the 

 machine runs down, to what extent may it be possible so to delay the 

 onset of molecular finality that some reaction may continue, at a lower 

 I'ate, until the succeeding day? ' And his answer is: ' The successful 

 solution of this problem is defined physiologically by the introduction 

 of the conception " haiaboJis}}!," as implying that energy derived from 

 the ' ' breaking down ' ' of the plasma itself . . . may be regarded as a 

 "secondary engine," functional in the absence of light, and evolved 

 as a last resort in failing plasma.' Katabolism persists as the ultimate 

 mechanism in the physiology of animal as contrasted with plant life, 

 but if the "suggestion just quoted is sound it originated, as the first 

 ' adaptation ' of the organism, to meet the factor of recurring night 



