127 



The Pines of Australia. 



Figure 65.— - Transverse section, showing a closed stage of concrescence 

 in the leaf, and where the three divisions are beginning to 

 individualise. C. glauca, x So. 



Figure 66. — This shows the concrescenl portions more distinctly, also 

 the fuller development of the ventral surfaces, and the 

 cuticle protuberances on them. The transfusion tissue 

 is well indicated by the pitted cells, and is seen to 

 occupy a large proportion of the leaf tissue. The divi- 

 sion of the median structure of the branchlet into three 

 bundles by obtruding medullary pith cells, and the 

 orieatation of the phloem (indicated by the darker cells) 

 are well brought out. C. glauca, x 8o. 



Figure 67. — In this section the decurrent channels or ventral surfaces 

 are seen exposed to the atmosphere. C. glauca, X 8o. 



Figure 68. — This transverse section is interesting in that one or two 

 elongated cuticle processes are seen on the lower of the 

 ■'_ assimilating surface. No oil , cavities occur in this or 

 t. previous sections, where also the endodermal and trans- 

 fusion cells are not arranged in any order. The ventral 

 surfaces on the two left concrescences have edged together, 

 and so shut out any communication between tlie air and 

 the stomata. C. glauca, x 8o. 



Cross sections of branchlets and decurrent leaves of Callitris glauca, R.Br, 



