GROWTH OF TREES. 351 



top shoot ; and the growth of the top [or end] shoots of the hranches 

 decreases downwards, but the top shoot of each branch is always longer 

 than the side shoots of the same branch. The top shoot is always 

 perpendicular and highest, or most so of any ; and this falling off from 

 the perpendicular towards the horizontal, becomes gradually more and 

 more so downwards to the lowest branch*. 



Qu. Is it owing to this perpendicular position, or to the greater 

 height, of the shoot, that the growth is greater ? 



Exp. — A Scotch Fir had its top or leading shoot cut off: it had four 

 principal second shoots or side branches immediately under the top shoot. 

 On the 1st of July I tied up one of these four side branches ; in three 

 days that young growing shoot became perpendicular, and in the same 

 line with the stock on which it grew, and it had also grown an inch 

 longer than any of the young shoots upon the other three side branches ; 

 so that it got the impression of the leading shoot. 



From the above principle in growth, we should suppose that the 

 greatest powers were at the top, and [that they] become weaker and 

 weaker downwards ; but we find that not to be the case. It is not 

 strength of action, but it is a principle of action : we may as well say 

 that the powers in a man's legs are greater than in any other part, 

 because they grow longer; but we know their powers from this 

 cause are weaker than other parts ; and we also know that the quickest 

 and longest growing shoot is the weakest in the vegetable, owing to the 

 same causes. For we may observe that, when anything affects the 

 general health of a vegetable, such as transplanting, severe winter, &c, 

 it is always the top shoot that shows signs of weakness most ; and upon 

 the same principle that the extremities in animals are weaker in their 

 living powers : and we may observe that although branches do not form 

 such long shoots as the top, yet they are first in action in the spring. 



When trees begin to throw out their leaves in the spring, or rather 

 form new shoots, it is always on their lower branches first, and in 

 gradual and regular succession upwards ; but still the upper will make 

 the greatest progress, having more the principle of growth. Also, if a 

 tree be newly planted, and does not take kindly to its new situation 

 and is weak, we find that the most vigorous parts are its lower 

 branches, strength decreasing upwards to the top shoot, which is the 

 weakest of the whole. Also, if we cut off the stem of a bean above the 

 fifth or sixth joint, new stalks will shoot out at the joints ; but it will 

 be at the first and second, not at the fourth, nor even at the third joint, 

 from the bottom. 



* The weeping-willow is an exception to this, and there may be many more. 



