24 GERMINATION OF THE SEED 



amides, and even ammonia compounds. These are all 

 soluble and diffusible. After transport to the growing points 

 the simpler bodies are again united to form proteins. 



10. Oxidases. — Respiration or oxidation, not being a 

 case of simple combustion, is probably due to the activity 

 of these enzymes which have the power of causing oxygen 

 to unite with various compounds. Under their influence, 

 starch and maltose are oxidized to carbon dioxide and water; 

 oils, as well as glycerine and fatty acids, are oxidized to 

 carbohydrates and possibly directly to carbon dioxide and 

 water. 



11. Summary. — A seed contains, in addition to the grow- 

 ing part, or embryo, a certain amount of food stored away 

 in a compact, insoluble form. To start growth it is necessary 

 that water be absorbed in order to supply a reagent for 

 rendering the food soluble, and to furnish a solvent for its 

 transport. Oxygen is also necessary to supply energy for 

 the building of new tissue and for the work of movement. 

 This results in the change of carbohydrates and oils ulti- 

 mately to carbon dioxide and water. A certain amount of 

 heat is necessary to aid in the absorption of water and in the 

 oxidation. The amount of heat varies for different seeds. 

 Food for the seedling consists of starch, oil, and protein, 

 the relative amounts of each varying for different seeds — 

 cereals containing large amounts of starch; cotton, flax, 

 and nuts much oil; and legumes much protein. To make 

 water unite with these compounds enzvmes are secreted bv 

 the germinating seed, and are stimulated by the absorption 

 of water and increased oxidation. Enzymes are not living 

 things; they are amorphous, catalytic agents, able to act 

 independently of the cells which produce them. Amylases 

 hydrolyze starch for the most part to maltose in germinating 

 seeds; lipases hydrolyze oil to glycerine and fatty acids 

 which later unite probably with potash to form soap. 

 Proteases hydrolyze proteins to simpler compounds, prin- 

 cipally albumoses, peptones, and amides. For oxidation, or 

 respiration as it is called, there are apparently necessary 

 enzymes called oxidases, which in some cases change starch 

 or maltose to carbon dioxide and water, and oils first to sugars 

 then to carbon dioxide and water. 



