IX] 



MAXIMUM GROWTH 



73 



But, apart from these annual length-increments of the 

 whole shoot and we must remember that all that applies 

 to the leader is also generally true of each branch it is 

 necessary to realise that the rapidity and maximum length 

 of growth of each internode along the shoot itself varies 

 in quite a similar manner. I quote the following tabular 

 statement from Biisgen. (See p. 74.) 



This bears out the general rule that the nodes are 

 close together at the base of the shoot, then become 

 further and further apart as we ascend, and then ap- 

 proximate more and more as we approach the tip, where 

 they are again close together ; and since the length of the 

 internode is an expression of the rapidity and energy of 

 growth during the growing season, the two are correlated 

 as already pointed out. 



But, as the table quoted above shows, there may be 

 variations e.g. in the Norway Maple, where a second 

 minimum occurs in the 9th and 10th internodes. Such 

 may be due to the occurrence of cold dry winds, excessive 

 sunshine and drought, and so forth, interrupting a tempo- 

 rary period of rapid growth. 



Moreover, a shoot which has already passed through 

 its period of normal growth, formed all its buds, and is 

 preparing to cast its leaves and pass over into the con- 



