THE SHOOT. 



85 



taking place, is called the. primary meristem (fig. 95). This 

 primary meristem has no definite limit below, but passes 

 insensibly into the permanent tissues. The tip of the shoot 

 may be either a sharp cone or a low dome. Between these 

 forms a complete series of gradations exists. Below the apex 

 the shoot begins to show a differentiation into a central axis 

 and lateral outgrowths. The first of these to appear are 

 swellings which form the leaves. Later, above the leaf 

 fundaments may appear the fundaments of the lateral shoots. 



Fig. 96.— Diagram of a section through a bud. V, the apex; i, 2, 3, 4, successively older 

 leaf fundaments; a, b, c, successively older branch fundaments; d, e, vascular bundles. 

 —After Hansen. 



The older leaves upon the sides of the axis outgrow the 

 younger ones and the developing axis, and arch over them 

 in such a way as to form a more or less compact structure, 

 which is a terminal bud. A bud is, then, an undeveloped 

 shoot, whose older leaves protect the younger, and particu- 

 larly the primary meristem (fig. 96). From the terminal 

 bud arise all the members of the primary shoot. 



102. Differences from root. — From what has been said of 

 the origin of the shoot, it will be observed that it is dis- 



