118 SCIENTIFIC AGRICULTURE. 



assumes the vicarious office of absorption. The invigorating 

 effect of a shower of rain oil the leaves of parched and wilted 

 plants, is seen long before the water could have reached the 

 roots and have been carried up to the leaves : this effect must 

 be produced, therefore, by the absorption of moisture by the 

 leaf. This action takes place mostly from the lower surface of 

 the leaf. 



Respiration in plants consists, as in animals, in the absorp- 

 tion of oxygen from the air, and the giving off of carbonic 

 acid. It is performed mainly by the leaves, but is performed 

 to some extent by other parts also : it continues without inter- 

 mission by day as well as by night, during the life of the plant 

 Respiration is most active during the processes of germination 

 and flowering: a constant supply of oxygen, and the daily 

 presence of light, are indispensable to the growth and vitality 

 of the plant 



Digestion comprises all those changes which the mineral, 

 aqueous and gaseous matters undergo after entering the plant, 

 until they are assimilated and become a part of the organism. 

 " It consists in the decomposition of carbonic acid by the green 

 tissues of the leaves, under the stimulus of the light, the fixa- 

 tion of the solid carbon, and the evolution of pure oxygen." 



[Wood. 



INFLORESCENCE. 



Inflorescence is the term used to indicate the peculiar 

 arrangement of flowers upon the stem and branches of plants ; 

 also their successive development in different parts of the same 

 plant Flowers are said to be terminal and axillary, in regard 

 to their position on the stem. 



Terminal flowers are placed at the end or summit of the 

 branch or flower stalk. 



Axillary flowers are placed in the angle formed by the 

 branch or leaf-stalk, and the primary central stem, or larger 

 lateral braaches. 



