138 PRACTICAL BOTANY. 



There is great variety in the character of the leaves in the 

 Conifercc. In some cases only foliage leaves are developed (Arau- 

 caria, Juniperus, Thuja). In one case only scale leaves are 

 formed (Phyllocladus), while here in Pinus we have both scale- 

 and foliage-leaves, the former alone being borne on the stronger 

 axes with unlimited growth, while the latter appear only on the 

 foliage shoots with limited growth. Specimens of different 

 members of the group should be examined and compared. 



II. Passing to the increment of growth of former 

 years, i.e. to the lower and older parts of the branch, 

 in the external appearance and arrangement of parts 

 they resemble that of the current year. The main 

 axis increases in thickness, and is more obviously 

 ligneous, while the limited foliage shoots drop off, 

 leaving scars which mark their former position. 



HISTOLOGY. THE STEM. 



It is best to work with material which has been treated for 

 some time with spirit ; by this means the resin, which would 

 otherwise clog the razor, is removed. 



I. Cut transverse sections of the Axis of a bud, and 

 treat with dilute potash for a few minutes : mount in 

 glycerine. 



Meanwhile other sections may be mounted in 

 Schulze's solution: examine with medium or low 

 power, and observe at the centre of the section 



1. The Pith, composed of cells, with intercellular 

 spaces, and thick cellulose walls (blue with Schulze's 

 solution) ; surrounding this a series of groups of smaller 

 constituents : these are 



2. The primary Vascular bundles. Note that 

 they are 



