12 MANUAL FOR SUGAR GROWERS. 



the formula CO^ ; this gas is produced whenever any 

 organic substance is burned, thus every fire is a 

 source of it ; it is present in the breath of all animals, 

 a human being giving off about seven hundred pints 

 every day, containing nearly eight ounces of carbon. 

 This gas is fatal to animal life, and unless some 

 means for its removal existed the whole atmosphere 

 would become poisonous and animal life would cease. 

 This gas is one of the most important plant-foods, 

 for the cells possessing the gi'een colouring matter 

 above referred to have the power of decomposing it, 

 retaining the carbon and returning the oxygen to the 

 atmosphere. Animal and vegetable life are thus de- 

 pendent on each other. Two things are necessary 

 for this process of plant-respiration : the green col- 

 ouring matter (or chlorophyll, as it is called) and 

 sunlight, — the process ceasing in the absence of light. 

 This affords an explanation of the fact that plants 

 become sickly if groT\Ti in rooms or dark places 

 where they are not exposed to sufficient light. 



It is from this source that all the carbon found in 

 vegetable structures and products is obtained ; and 

 what an imj)ortant part of plant life, and how entirely 

 the production of such substances as sugar depends 

 on it, will be readily recognised if it be remembered 

 that sugar contains nearly half its own weight of 

 carbon. 



The first substance produced by the plant from 

 the carbon obtained by respiration is starch ; this 

 is composed of carbon, oxygen, and hydi'ogen, hav- 

 ing the formula CgHjoO. ; the starch thus formed is 

 quickly converted into other and soluble substances, 



