The Anatomy and Physiology of Plants 69 



port of its living matter. The first thing we can find that 

 is formed in this way is starch, but it is probable that 

 really some form of sugar for the immediate consumption 

 of the growing plant is first formed, though it cannot be 

 detected. Starch is called a carbohydrate because it con- 

 sists of carbon, oxygen, and hydrogen. Carbohydrates 

 are used by plants for building purposes and as a storage 

 form for food to be used in subsequent growth. Starch 

 is largely stored up in seeds, but in some seeds is very 

 largely changed into oil, as in the cotton seed and others. 

 When we put a seed in the ground and it imbibes water 

 and begins to germinate, the starch is transformed into a 

 sort of sugar which the growing plant can use, for starch 

 as starch is not digestible by animals or plants. 



In the germinating seed there is a sort of ferment formed 

 that changes starch to sugar without itself being in any 

 way changed. We have the same thing called diastase in 

 our saHva, and when we eat starchy food this is mixed with 

 it and changes the starch to a glucoside or sort of sugar, 

 so that it is made digestible. Starch, then, is a storage 

 for food. It is stored in the cells of the plant and when 

 active growth begins it changes into sugar for use. Take 

 a potato that has sprouted, and on cooking it you will find 

 that it has become clammy and has a sweetish taste, 

 owing to this transformation of the starch. In seeds 

 where the food is stored in the form of oil the oil is trans- 

 formed back to starch and the starch to sugar for the use 

 of the plant till it can develop green leaves and get more 

 material from the air for the manufacture of more starch. 

 From the starch all the long list of substances called 

 carbohydrates is formed; the sugars, oils, acids, and 



