86 Cell-Pedigrees 



Let us return now to the shoot during its first year of 

 vegetation. At the end of the summer it perishes. A 

 lateral bud in one of the basal leaf-whorls, however, con- 

 tinues to live, and develops during the next year into a 

 new shoot, which grows stronger and larger than the first 

 one, but does not yet bear any organs of fructification. 

 This course continues for several years, until the plant 

 has become quite vigorous. Sometimes the third or one 

 of the following shoots grows downward into the ground, 

 to form the rhizome, which, from now on, forms the 

 main-shoot of the plant, branching beneath the ground 

 and sending up into the air the leaf-bearing and spore- 

 bearing shoots. These are distinct in Equisetum arvense 

 and some other species. In the spring the pale, fertile 

 unbranching shoots arise, in the summer the extensively 

 spreading, green but sterile branches. 



The cellular pedigree of the whole large plant would 

 very soon present an inextricable picture. To avoid this 

 danger, we must mark especially the main lines, perhaps 

 by indicating them by heavier marks. We must also 

 draw the lines as straight as possible. Supposing all of 

 this executed, we get a pedigree of the apical cells which 

 in the picture stands out clearly as a connected system, 

 and to which all the rest is laterally added. We shall 

 call the lines of the pedigree of the apical cells the 

 branches, the other ramifications the twigs. In order to 

 avoid misunderstandings, it must be remembered, that 

 the pedigree of apical cells does not consist exclusively 

 of apical cells, since these do not originate directly from 

 each other. 



According to this definition the development of the 

 twigs of the pedigree is always limited, only in the 

 branches resides the ability of new ramifications, and 



