THE TISSUES OF PLANTS. 31 



from that of the majority of mosses. In Horsetails, for 

 example, it is an inverted triangular pyramid, having a 

 convex base. The segments (daughter- cells) are cut off by 

 alternating partitions parallel to the plane sides of the 

 pyramid, as in the mosses. In some mosses and ferns, how- 

 ever, the apical cell is wedge-shaped — i.e., with only two 

 surfaces — and in such cases two instead of three rows of 

 meristem-cells are formed. 



56. In the flowering plants the primary meristem is de- 

 veloped from a group of cells, instead of froni a single one; 

 they therefore have no apical cell. This group of cells 

 occupies approximately the same position in the organs of 

 flowering plants as the apical cell does in the mosses and 

 ferns; it is composed of cells which have the power of 

 indefinite division and subdivision. 



57. The apical cell and its actively growing daughter- 

 cells in its immediate vicinity, or, in the case of the flower- 

 ing plants, the apical group of cells with their daughter- 

 cells, constitute the Growing Point or Vegetative Point 

 {pmictum vegetationis) of the organ. When this active 

 portion is conical in shape it is also called the Vegetative 

 Cone. 



Practical Studieg.-^a) Make very thin longitudinal sections of a 

 root of Indian corn. The large strong roots wliich first start out 

 from the germinating grain, and tlie youngest states of tliose which 

 appear just above the ground, upon the large plants, are best for 

 these specimens. Stain some of the sections with carmine. 



(J) Malie very thin longitudinal sections of the opening buds of the 

 lilac or elder. 



(c) Make similar sections of the tips of the young shoots of aspara- 

 gus. Stain with carmine. 



(tQ Make cross and longitudinal sections of the youngest states 

 of the stems of the pumpkin, squash, and asparagus, and compare 

 with similar sections of older parts. 



