THE ACTIVITIES OF THE ORGANISM 89 



organism which have become associated with the 

 animal and incorporated in its tissues). In all these 

 cases the presence of this chlorophyllian substance 

 confers on the organism the power of effecting the 

 compensatory energy-transformation, by the aid of 

 which carbon dioxide and water are built up into 

 starch. What this transformation is, and what are 

 the steps by which the carbon dioxide and water be- 

 come carbohydrate we do not exactly know. Solar 

 radiation impinging upon an inorganic substance is 

 partly reflected and partly absorbed. The absorbed 

 fraction may become transformed in such a way as to 

 render the substance phosphorescent, or it may trans- 

 form into chemical energy, as when light impinges on 

 a photographic plate, but as a general rule it is trans- 

 formed into heat. In the green plant, however, the 

 transformation of radiation into heat does not occur — 

 at least the heating is very small — and it passes directly 

 or indirectly into the potential chemical energy of the 

 starch which is synthesised. We must regard this 

 power of absorbing radiation and utilising it in com- 

 pensatory transformations as a general character of 

 protoplasm. It is true that it is now specialised in 

 the cells containing the chlorophyll bodies, but there 

 are indications that it may be present in the tissues 

 of the animal devoid of chlorophyll. 



Other anabolic transformations occur in the animal. 

 The food-stuffs which are absorbed from the intestine 

 are substances which have undergone dissociations, 

 the nature of which is such as to render them capable 

 of absorption and of reconstruction. These anabolic 

 changes in the higher animal are exceptional, and their 

 usefulness lies in the fact that by their means substances 

 become capable of being transported by the tissue 

 fluids of the body. 



