198 Proceedings of the Royal Physical Society. 



passage of plastic food material, and there seems to be no 

 reason to believe that their death is in any way due to a 

 want of sufficient nutriment, though it is quite possible that 

 some specific want may occur as far as their chemistry is 

 concerned. It would seem likely that the highly specialised 

 cells of plants undergo death on account of their protoplasm 

 passing gradually into more stable organic substances, which 

 have lost the essential functions of life. The protoplasm of 

 such organs as have complied with the requirements of the 

 life of the plant, and are destined for death, is said in some 

 cases to be reabsorbed into other parts of the plant in the 

 form of plastic material, and the dead cells are often found 

 empty of their protoplasm. It seems also that cells of 

 organs which are used for storage purposes do not regain 

 their vitality when the food material is recovered for the use 

 of the growing shoots, and it would appear from this that the 

 kind of specialisation found in plant cells leads to their death 

 in spite of abundant food material. 



It is in plants and the lowest forms of life that anabolism 

 at first sight seems to be most evident. This is due to the 

 greater part of the food being used solely for growth, whereas 

 in the higher animals the energising or katabolism is so 

 marked as in more or less degree to keep pace with the 

 anabolism when adult life is attained. 



The power of simple anabolism probably decreases on 

 passing upwards both in animals and plants, in fact, the 

 rapidity of growth and division in some of the lowest forms 

 of life is immeasurably greater than in the higher forms. 

 One judges of an animal chiefly by its katabolism, and of a 

 plant by its stable products of anabolism, though in both the 

 anabolism is the essential factor in their evolution. In 

 animals, the more elaborate the anabolism and unstable its 

 products, within healthy limits, the more governable and 

 elaborate would be the katabolism. In plants, on the other 

 hand, the more stable the products of anabolism became, the 

 less would be the katabolism. As regards the lower forms 

 of life, the greater the anabolism the greater would be the 

 potential of katabolism. Whether the katabolism became 

 actual, governable, and elaborate, would depend upon whether 



