222 COLLEGE BOTANY 



tio'U, that is, the carbon dioxide and water, may be used by the 

 plant or returned to the air through the leaves. 



Respiration and Photosynthesis. — (1) Respiration occurs in 

 the protoplasm of the cells throughout the plant, while photo- 

 synthesis occurs only in the chloroplasts. (2) Kespiration is a 

 process of oxidation and breaking down of compounds resulting 

 in the liberation of latent energy, while photosynthesis is a 

 process of building up of compounds and storage of latent energy. 

 (3) Respiration uses oxygen and liberates water and carbon 

 dioxide, while photosynthesis uses water and carbon dioxide and 

 liberates oxygen. (4) Respiration is active in the presence or 

 absence of light, but photosynth^is requires sunlight. (5) 

 Photosynthesis is carried on by the energy derived from sun- 

 light and life processes are carried on by the energy derived 

 from respiration. 



Respiration and Starvation. — When animals are deprived of 

 food they lose in actual weight, regardless of the supply of water 

 and air, because they are using their reserve or stored supply of 

 food. In the same manner a green plant deprived of sunlight, 

 which is necessary for the formation of true plant food, but 

 supplied with all necessary water, air, minerals and nitrogen, 

 will lose in actual or dry weight, because it is also using its 

 reserve or stored supply of food. The animal must have organic 

 food from which to construct its own tissues. The plant mami- 

 factures its own food from the raw materials and this cannot be 

 done without sunlight. Therefore, depriving the animal of or- 

 ganic food and the plant of sunlight result in starvation. Seeds 

 germinated in total darkness will increase in total bulk, but de- 

 crease in actual dry weight, because the reserved foods are used in 

 the process of growth. This loss of weight is due to the respira- 



