STEM ARBOREOUS TYPE 99 



connection with the leaves. These bundles are therefore 

 cauline. 



II. Cut transverse sections of the stem of Draccena immedi- 

 ately below the apical tuft of leaves : mount in glycerine, and 

 examine under a low power. Observe that the arrangement of 

 the tissues, as well as the character of the vascular bundles, is 

 similar to that in the Maize : there is, however, a peripheral 

 cortex, which is not found in the Maize. Note that the cells of 

 the inner limit of the cortex are quiescent, and not under- 

 going division. 



III. Cut transverse sections of the stem of Draccena at a 

 point one foot or more from the apex, and mount in glycerine. 

 Examine with a low power, and observe 



1. A well-marked epidermis. Beneath this 



2. A band of cork. 



3. A broad belt of cortical parenchyma many cells of which 

 contain crystals (raphides, &c.). Here and there a vascular 

 bundle will be seen in the cortex : these are bundles of the 

 leaf-trace, passing inwards from the leaves. 



4. At the inner limit of this the cells are not quiescent, as in 

 the younger part of the stem, but there is an actively dividing 

 merismatic ring, which gives rise internally to new vascular 

 bundles, and externally to fresh cortical cells. The new 

 bundles thus formed are cauline, having no direct connection 

 with the leaves, and are embedded in lignified ground-tissue. 

 These together form a dense ring. 



5. Centrally, there still remains undisturbed that arrange- 

 ment of thin-walled parenchyma and vascular bundles which 

 has been above noted in the young stem as being similar to 

 that in the internode of Maize : the primary or common 

 bundles may be distinguished from the secondary or cauline 

 bundles, not only by their arrangement, but also by their 

 structure, the latter having a denser sclerenchymatous sheath 

 and smaller vascular elements than the former. 



Note the passage of these central bundles outwards to the 

 bases of the leaves : they are common bundles. Observe also 

 the mode of formation of the cauline bundles. 



H 2 



