BEGINNING OF THE STRUGGLE. 



53 



■i 



ill height aud spread of crown. Growth iii this way 

 was going on uncliecked among the young trees be- 

 fore the crowns met, but now only the upward-grow- 

 ing branches can develop freely. The leaves at the 

 ends of the side branches have now less room and, above 

 all, less light, for they are crowded and thrust aside by 

 those of the other trees. Very often they are bruised 

 by thrashing against 

 their neighbors when 

 the wind blows, or 

 even broken off while 

 still in the bud. 

 Leaves exj^osed to 

 such dangers are un- 

 healthy. They tran- 

 spire less than the 

 healthy, undisturbed 

 leaves of the upx^er 

 part of the crown, 

 and more and more 

 of the undigested 

 food from the roots 

 goes to the stronger 

 leaves at the toj^ 

 as the assimilating 

 power of the side 

 leaves dwindles with the loss of light. The young 

 branches share the fortunes of their leaves and are vigor- 

 ous or sickly according to the condition of the latter. For 

 this reason the growth of the tops increases, while that of 

 the lower lateral branches, as the tops cover them with a 

 deeper and deeper shade, becomes less and less. Gradu- 

 ally it ceases altogether, and the branches perish. This 



Fig. 50. — Small saplings of White Pino grow- 

 ing thickly together. Milford, Pa. The 

 space hetween each clvister or whurl of side 

 hranches marks one year's growth. These 

 young Pines are beginning to grow rajiidly 

 in height because they can no longer spread 

 at the sides. 



