[Chap. XIX SUBSTANCES MADE FROM FOOD 175 



Table 6. Enzymes, Subtrates, and End Products of Enzyme Action 



Enzyme 



Substrate 



End Products 



Diastase 



Maltase 



Sucrase 



Inulase 



Hemicellulases 



Pectosinase 



Pectase 



Pectinase 



Tannase 



Lipase 



Peptase (pepsin) 



Ereptase (trypsin) 



Starch 



Maltose 



Sucrose 



Inulin 



Hemicelluloses 



Pectose 



Pectin 



Pectic acid 



Tannin 



Fats and oils 



Proteins 



Proteins and peptones 



Glucose 



Glucose 



Glucose and fructose 



Fructose 



Simple sugars 



Pectin 



Pectic acid 



Simple sugars and acids 



Glucose and gallic acids 



Glycerin and fatty acids 



Soluble peptones 



Amino acids 



rickets were the first symptoms of vitamin deficiency to be clearly demon- 

 strated. 



Vitamins, or their precursors, are manufactured mostly by plants. They 

 accumulate in certain animal tissues and in milk from the plants eaten by 

 the animals. Carotene is a precursor of vitamin A, and ergosterol of 

 vitamin D. The bacteria in the alimentary tracts of animals probably 

 manufacture certain vitamins. 



Methods of detecting the manufacture of vitamins in plants and their 

 effects upon the development of plants are not well established. There is 

 evidence, however, that vitamins also affect plants in certain funda- 

 mental ways. 



Hormones. These substances constitute another group of organic com- 

 pounds that produce profound physiological effects when present in 

 extremely minute amounts. Like the enzymes and vitamins, they influ- 

 ence certain basic biological processes. Their presence or absence is 

 recognized by certain symptoms of development. They were first defi- 

 nitely discovered in animals as secretions of certain glands. In 1928 the 

 presence of similar substances in plants was definitely established. Three 

 of them have been isolated from plants and their chemical constitution 

 is known. They were called auxins; others have been called calines; but 

 in a general textbook we shall refer to all of them as hormones. 



Hormones influence the enlargement of cells, the formation of roots, 

 and the dominance of certain parts of plants over others. There are prob- 

 ably very few, if any, developmental processes in plants that are not 

 influenced by them, but many experiments will have to be performed 



