STEM STRUCTURE 85 



increasing slowly in size for indefinite periods, while animals reach 

 a maximum size and grow no larger, no matter how old they become. 

 The reason is probably that in plants, little energy is required, 

 hence little food is used in oxidation and more is left for additional 

 growth, whereas in animals, which use more energy, a point is 

 reached, where the nutritive processes are just balanced by oxida- 

 tion and further growth ceases. As soon as the destructive proc- 

 esses exceed the constructive, old age enters and finally death 

 itself. 



COLLATERAL READING 



Science of Plant Life, Transeau, pp. 118-136; Botany of Crop Plants, 

 Robbins, pp. 33-41; Fundamentals of Botany, Gager, pp. 61-68; Plant 

 Anatomy, Stevens, pp. 28-60; Principles of Botany, Bergen and Davis, 

 pp. 57-79; Botany for Schools, Atkinson, pp. 51-60; Introduction to Botany, 

 Stevens, pp. 45-64; Plant Life and Plant Uses, Coulter, pp. 162-185; Plant 

 Structures, Coulter, pp. 232-237; Elementary Botany, Coulter, pp. 224-252; 

 Applied Biology, Bigelow, pp. 163-188; Elementary Biology, Peabody and 

 Hunt, pp. 45-52; Biology, Coleman and Bailey, pp. 59-72; Plant Relations, 

 Coulter, pp. 83-87. 



