STATE HORTICULTURAL SOCIETY. 145 



assured that the amount of absorption by roots is very great; yet 

 the facts surpass the most liberal estimates made upon other than 

 experimental data. It is indeed marvelous how much water the roots 

 of plants are capable of taking out of the soil which is simply moist, 

 but from which no tile or other drain would receive a drop of water. 

 In fact roots do not take the water as a liquid and absorb it as does a 

 s]ionge. Water is really made up of excessive ruinate solid particles, 

 which the scientists call " molt^cules." If we can, in imagination, 

 reduce grains of sand to sizes too small to be visible even under the 

 microscope, but still retain their solid character as grains, we shall 

 have a crude idea of the mech;inical composition of water. These 

 exceedingly minute water ptirticles (molecules) have little attraction 

 among themselves, hence move fkeely upon each other and we call 

 the mass a liquid. But there is a strong molecular attraction be- 

 tween the solid elements of water and the particles of the soil. and. 

 up to a certain projjortion of water, there is in the mixture of the 

 two absolutely no liquid existing. The solid molecules of water are 

 held as such, in cohesion with the solid soil particles, thus utterly 

 destroying the characteristic of a liquid. Now we have seen that 

 the root hairs exactly fit themselves to the surfaces of the particles 

 of soil; actual contact between the two abundantly exists. The walls 

 of these root hairs, though a])]iareHtly imperforate even under our 

 best microscopes, have a strong attraction for water. The adhesive 

 power of the surfaces of the soil elements is overcome, and the mole- 

 cules of water leave the latter and pass into the substance of the 

 wall of the hair, to be transferred thence to the root, and from the 

 root through the stem to the leaves of the plant. Without attempt- 

 ing further explanation of this process of root absorbtion, it may be 

 remarked that the properties of molecular attraction, and what is 

 known as diffusion — dependent upon the former — does sufficiently 

 elucidate the phen(nnenon. Let us emphasize, however, the absolute 

 need of actual contact between the plant and the soil for such ab- 

 sorjjtion to take place at all. The water molecules will not fly 

 through s])ace, however limited, to reach the jdant tissues, however 

 powerful the absorptive property of the latter. . We can* therefore, 

 clearly see the reason of the partial liquefaction of the walls of the 

 root hairs and their close fitting in this plastic state to the irregular- 

 ities of surface of the granules of soil. 



Of course the better developed the root hairs the greatei- the 

 absorptive capacity, and, other things being equal, the greater the 

 number of fine rootlets, the more efficient the root system. Such 

 rootlets, as we have seen, are far more numerous in rich soils, and 

 we may now add in moist soils rather than in wet soils, in thorough- 

 ly pulverized or friable soils rather in those containing hard lumps 

 or in a mortar-like consistency. When roots are surrounded l)y stag- 

 nant water, few or no hairs exist. Nomimilly, aquatic jilants have 

 no root hairs. 



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