154 PRACTICAL BOTANY. 



V. Cut median longitudinal sections of the apex of 

 the root of Pinus. This may be easiest done by cutting 

 longitudinal sections of the mature embryo in the seed. 

 Treat with potash till they are transparent, and mount 

 in glycerine. Observe : 



1. The central Plerome cylinder, recognised as in 

 the Sunflower and the Maize. It is Bounded off at the 

 apex, and throughout is quite distinct from 



2. The Periblem, which surrounds it. This is the 

 formative tissue of the cortex. Outside this no true 

 epidermis is to be found ; but at the apex is 



3. A Root-cap, which is formed by the active 

 division of the cells of the periblem at the apex of the 

 root. 



Compare this arrangement of the apical meristem 

 with those types seen in the roots of Angiosperms. 



REPRODUCTIVE ORGANS. 



We have seen at the apex of the ordinary vegetative 

 branch in spring, an apical bud surrounded by a 

 number of lateral buds, all of which normally develop 

 into vegetative axes of the type above described. 

 The reproductive organs of Pinus are produced on 

 buds corresponding in position to these : they are easily 

 recognised, even at an early stage of development, with 

 the naked eye. 



The following observations should be made upon museum 

 specimens, otherwise they oould only be made at intervals, 

 according to the .period of development of the organs in question. 



I. Male inflorescence. A. Note that the inflores- 

 cence while young, appears as a bud covered with brown 





