Ch. IV, S] 



RESPIRATION OF PLANTS 



169 



may be proven by suitable methods, as explained with our 

 picture (Fig. 117). It is this same respiration heat, intensi- 

 fied and regulated, which fields the "blood heat " of animals. 

 It ■nill now Ije worth while to summarize the contrast be- 

 tween photos},Tithesis and respiration, as is possible in a 

 table. 



Photosynthesis 

 Occurs only in green plants 



Takes place only in the chloro- 

 phyll grains 

 Proceeds only in light 



Constructs food 

 Increases weight 

 Absorbs carbon dioxide 

 Releases oxygen 

 Forms grape sugar from car- 

 bon choxide and water 

 Stores enersT,- 



Respiration 



Occurs equally in all plants 

 and animals 



Takes place in all li^-ing 

 protoplasm 



Proceeds in both light and 

 darkness 



Destroys food 



Lessens weight 



Releases carbon dioxide 



Absorbs oxygen 



Reduces grape sugar to car- 

 bon dioxide and water 



Releases energy.- 



Thus respiration destroys the product of photosj-nthesis, 

 but in the process develops the dri^dng power for plant and 

 animal hfe. 



There is a form or phase of respiration so important as 

 to demand special treatment, and that is fermextatiox. 

 If some Yeast (which is a unicellular microscopic plant, to 

 be fully described in Part II of this book), in the form of 

 ordinary compressed Yeast, be placed in a flask with water 

 and sugar, and stood in a warm place, -n-ithin a few minutes 

 the mixture begins to "work" or ferment, producing many 

 fine bubbles which rise through the liquid and form a froth at 

 the top. If. from this flask a bent outlet tube be led under 

 limewater (Fig. US'), through which the escaping gas can rise, 

 then the hmewater vnll turn very milky, pro\-ing the gas 

 to be carbon dioxide. After fermentation has ceased, the 



