CHAPTER XXX 1 1 



PLANT CONSTRUCTION 



IN this chapter it is not our intention to discuss the minute study 

 of the plant body with the help of a microscope, which is neces- 

 sarily a branch of indoor work. We would rather suggest what can 

 be done in the field, with sharp eyes and the occasional use of a 

 pocket-knife. It is perfectly obvious that the precautions which 

 engineers take in building pillars, in supporting weights on brackets, 

 and so forth, must be likewise taken when a huge trunk grows 

 upward to the sky, and weighty branches with their thousands of 

 leaves spring out in all directions from its sides. The nature student 

 should notice how the heaviest part of a tree stem is at its base, 

 and how the roots very often form buttresses and so give it stability. 

 By growing large varieties of Indian corn, a similar use can be seen 

 in the case of the roots which are pushed out from the lowermost 

 joints of the stem as the plant increases in height and the swollen 

 heads of fruit grow heavier. 



It would be interesting to examine the junctions of branches 

 with the main stem by cutting down to the pith. In those plants 

 where the latter is comparatively wide, as in Figure 226, it will be 

 found that a band of wood cuts off one cavity from another and 

 so gives strength to what would otherwise be a weak spot. In the 

 case of branches such as those of the apple, where the pith cavity is 

 exceedingly small, there is a continuous passage from stem to branch.* 



* Our attention was called to this interesting point by Mr John Gibbs, the Essex botanist. 



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