145 



sixth is the presence, in the former, of parts of living plants, we 

 must conclude that the change in the air is due to the vital acti- 

 vities of the roots, stems, leaves, flowers, and seeds. But an 

 absorption of oxygen and an evolution of carbon dioxide, we 

 have learned, is the outward indication of the cell- process called 



that plants respire. 



It will be seen here that plant respiration is not confined to the 

 leaves. Nothing can be more misleading than to speak of leaves 

 as the " lungs of plants." If any comparison at all is to be made 

 they could better be called the stomachs of plants, for in them 

 processes of digestion go on with as much, if not more, vigor 

 than does respiration. Moreover many kinds of plants such as 



n then 



withst: 



• all the 



s have been dropped, c 



suppl 



ied, water a 



nd air may be abund; 



int, but without respiration 



life is 



impossible. 



The power to respir 



e marks the chief difference 



betwe 



:en the livii 



ng and the non-livin 



g. In the realm of living 



thing 



sit is univer 



sal and incessant. I 



t is always in all essentials, 



the s 



ame proces 



s, whether in plants c 



>r in animals. The failure 



to re< 



:ognize this 



fact gave rise in the 



latter half of the last cen- 



tury 



to the docti 



rine of vital dualism. 



Because of the supposed 



differ- 



ence betwee 



n animal and plant re; 



spiration, it was argued that 



there 



were two k: 



inds of life. A cleare 



:r understanding of the vital 



No clearly defined line 



As great differences exist between certain animals, and between 

 certain plants, as are found between animals and plants. But 

 the process of respiration is everywhere the same. Even dry 

 seeds, which certain German physiologists have considered as in 

 a condition of " Scheintodt" (apparent death), are respiring. The 

 boquets in our vases, the celery and lettuce on our tables, the 

 potatoes and apples in our cellars, as well as the trees, shrubs 

 and herbs, indoors and out, are constantly, day and night, taking 



