40 



General Botany 



therefore, say that most of the work of the world, including that 

 done by men and animals, is accomplished by the use of energy 

 accumulated by plants in photosynthesis. 



Fig. 23. Diagram of the process of photosynthesis, showing primary and secondary products. 



The importance of photosynthesis as a source of wealth. The 

 value of all the plant products of field and forest for one year is 

 many times as great as the value of all the minerals dug from the 

 earth during the same amount of time. Furthermore, minerals 

 are limited in amount and are gradually being exhausted ; while 

 on the other hand the products of photosynthesis are being con- 

 stantly renewed, and we may continue to collect them indefinitely. 



Summary of photosynthesis. We may summarize the facts 

 we have learned regarding the process of photosynthesis by liken- 

 ing it to a manufacturing process of human invention : 



is the green tissue, especially that of the leaves. 



are the cells. 



is the chloroplasts and the chlorophyll. 



is the sunlight. 



are the carbon dioxide and water (CO2 and H2O) . 



is the stomata and intercellular spaces, and 

 the water-conducting tissue. 



are carbohydrates : sugars (CeHioOe) and 

 starches (CeHioOs)^. 



is the food-conducting tissues, and it works 

 both day and night. 



is oxygen, which escapes through the inter- 

 cellular spaces and the stomata. 



are all the hours of sunHght. 



The factory 



The workrooms 



The machinery 



The energy 



The raw materials 



The supply department 



The products 



The forwarding department 



The waste material 



The working hours 



