RADICATION OF TLANTS. 



flowers first fertilised for their own developement. It is 

 a foot, that many plants will not repay the trouble of cul- 

 tivation, if the cHmatic conditions are not sufliciently 

 favourable to effect the thorough ripening of all the 

 flowers, but serve only to ripen part of them. 



With oats it often happens that in warm moist weather 

 side-branches will spring from the axils of the leaves, 

 when the principal culm is already shooting into ear ; 

 whence it happens, that at the end of the period of vegeta- 

 tion the plant is found to bear both ripe and unripe seeds. 



The condition of the soil, as to porosity or compactness, 

 influences the radication of plants. The fine filaments of 

 the root, which are often coated with cork-like matter, 

 are lengthened by the formation of new cells at their 

 extremities, and they are obliged to exert a certain pres- 

 sure, to force their way through the particles of earth. 



The root-fibrils will always extend in that direction in 

 which they encounter the least resistance ; and this 

 lengthening necessarily presupposes that the pressure 

 wherewith the new-formed cells push aside the particles 

 of earth, must be somewhat greater than the cohesion of 

 the particles. The strength with which the root-fibres 

 force their way through the soil, is not equally great in 

 all plants. Those plants which have roots formed of 

 very fine fibres, are but imperfectly developed in stiff', 

 heavy soils, wherein other plants with thicker and stiffer 

 root-fibres will grow luxuriantly. The very resistance 

 which the heavy soil opposes to the spreading of the 

 roots of such plants tends to strengthen their fibres. 



Of the cereals, wheat, with a comparatively feeble 

 ramification of roots in the upper layers of the soil, still 

 forms the strongest roots, which often penetrate several 

 feet down into the subsoil ; for a certain degree of com- 

 pactness in the surface soil is favourable to the develope- 



