Significance of the Apical Cell 85 



individual, the main stem remains simple, and, since the 

 first shoot never bears a sporophore without modification 

 of its activity, it ends witl} the death of the shoot at the 

 end of the 'first summer. 



Each segment that separates from the apical cell di- 

 vides first into an upper and a lower half; these, through 

 further walls, into a body of tissue, from which now all 

 the cells of the respective part of the internode and the 

 leaf-whorl arise. The sequence of division has been ex- 

 plained by Cramer and Rees and can be found in the 

 Lehrbuch der Botanik, of Sachs and Goebel. Further- 

 more, there should be emphasized, first of all, the fact 

 that, in the outer cell-layer of the body of tissue, and 

 alternating with the teeth of the leaf-blade, favored cells 

 are formed, each of which can grow into a lateral shoot. 

 The green shoots of older plants as a rule actually bear, 

 in every leaf-whorl, a circle of as many branches as the 

 whorl has members. But, in the first shoot, they usually 

 do not reach development. Every lateral bud, when de- 

 veloping into a shoot, possesses an apical cell, which starts 

 the development of the branch in the same manner as the 

 terminal cell of the main shoot. 



Thus in every branch the apical cell again forms the 

 main line of the pedigree. It is true that this line does 

 not join the main stem in a simple manner but it can be 

 clearly traced back, through the first divisions of the 

 segment, to the stem. Now every segment, and within 

 it, during their first cleavages, those cells from the later 

 divisions of which the apical cells of the lateral branches 

 arise, we shall regard as the main stem of our pedigree. 

 All other cell-sequences will be considered as lateral 

 branches, for only in this manner can we get a clear 

 picture. 



