420 



branch exclusively, and not the axis above the place at which the 

 branch goes off. 



4. It is to be observed that on most plants the angle widens as we 

 ascend from the base to the middle, and then nan-ows rapidly as we 

 ascend from the middle to the apex. This is the case both with the 

 branches of the plant and the veins of the leaves ; but in some cases 

 the angle is widest at the foot and naiTows as we ascend. Thus the 

 birch begins at nearly 50 deg., and speedily comes down to 35 and 

 even 30 deg. The Salvia (red) begins at 45 deg., and speedily reaches 

 its average of 35 deg. The white lilac begins at 58 deg., and comes 

 down to 50 and 45 deg. The same holds of some, but not all, kinds 

 of poplar. In the above table the angle taken is supposed to be the 

 average of those fully developed, being commonly the third or fourth 

 from the base of the leaf. 



5. In plants with spines. All spines and branches tending to be- 

 come spines have an angle wider than the normal one. Have not old, 

 decaying trees the same ? 



6. Exceptions. — While I am convinced of the general tendency of 

 the stemage and leafage to take the same form, I am prepared to be- 

 lieve that there may be exceptions. I am inclined to think that the 

 exceptions will fall under the following rule : — The genus, as a whole, 

 will have a correspondence between leaf and branch ; and most of the 

 species under the genus will vary in leaf when they depart in branch 

 from the normal form ; but there will be found varieties of a singular 

 description (I suspect some kinds of poplar), especially monsters, 

 which will differ from the genus in the stem, while they retain the 

 generic leaf, or vice versa. 



4. * On Fossil Woods from Antigua and Australia ;' by R. Bryson, 

 Esq. Mr. Bryson exhibited specimens of silicified woods from An- 

 tigua and Australia, the former being both exogenous and endoge- 

 nous, while the latter were coniferous. Some of the specimens were 

 about a foot in diameter, and were beautifully polished by Mr. Young. 

 Mr. Bryson made some remarks on the process of silicification, and 

 pointed out the difference of appearance presented by the woods. 

 Some were completely opalized and hard throughout ; others had por- 

 tions, either external or internal, which were less completely silicified, 

 and in a friable state. In this latter state the Australian woods 

 showed the coniferous structure, while the opalized forms did not 

 show disks under the microscope. 



