THE THREE PHASES OF GROWTH. 



417 



the perfectly homogeneous cell-tissue of which the embryo at first consisted. 

 All the growing-points, therefore, are directly derived from the primary embryonic 

 tissue; in such a manner, however, that we have to sup])ose the substance of the 

 latter as being nourished and continually increasing in quantity. If the growth of the 

 plant were entirely confined to that of the growing-points, it would consist in an 

 exceedingly slow increase in volume of 

 the original embryonic tissue. We might 

 imagine all these small growing-points, 

 so to speak, cut off and then united into 

 one whole : we should then have a very 

 small structure, consisting of nothing 

 but embryonic tissue, from which the 

 individual growing-points would stand 

 out as protuberances. Having clearly 

 apprehended this, it is now obvious that 

 in reality the various growing-points in 

 the developing plant described above 

 have been pushed asunder and removed 

 to a distance from one another; between 

 each two of them a longer or shorter 

 piece of shoot-axis (or in the roots a 

 piece of mature root-tissue) has been 

 intercalated. This mutual separa- 

 tion of the growing-points, or interca- 

 lation of new masses of tissue between 

 them, is moreover, as is easily observed, 

 effected in the second phase of growth ; 

 and this always consists fundamentally 

 simply in the elongation of those por- 

 tions of tissue which are situated at the 

 base of each growing-point. 



On reviewing these processes ac- 

 cording to all that has been said so 

 far, it must be allowed that the growth 

 of a plant, even wholly apart from the 

 processes taking place in the individual 

 cells, is a very remarkable and extremely 

 complicated phenomenon, which the 

 student must try to apprehend perfectly 

 if he wishes to obtain any clear ideas 



at all of the life and being of plants. Considering the difficulty which the right 

 understanding of these processes must necessarily present to the beginner, it will 

 not be superfluous to take into consideration yet a few other examples. 



Fig. 255 illustrates, also diagrammatically, the processes in question in the case of 

 an erect monocotyledonous plant. The figure represents a plant of the INIaize (Indian 

 Corn); but would hold good, with but few alterations, for a Palm, and numerous other 



[3] EC 



Fig. 255.— Diagram showing the distribution of the phases of 

 growth in a Monocotyledon. 



