ORGANS OF KrTEITIOX. 149 



has given the follo^ving table of plants in -which the angles of 

 branching and renation were foiuid to agree,— the angles being 

 taken immediately below the points where the branches and veins 

 were given oflf : — 



Deg. 



Beech 45 



Oak (large branches) 50 



" (small branches and veins) . . . 65 — 70 



Cherry 50 



Portugal Laurel 50—60 



Bav Laurel 50—60 



Holly 55—60 



Ehododendron 60 



Eose 50 



Laburnum (small branches) . . . .60 



Box, about 60 



Thistle 60—70 



Thorn (lowest branches) .... 35 — 50 



Ash 60 



Bird Cherry 60 



Eed Dog-wood 45 



Alder . 50 



Mountain Ash 45 



&c., &c. 

 Dr. McCosh also believes " that the analogy between the 

 skeleton of the leaf, and the skeleton of the branch, may be seen 

 in a number of other points ; thus, some trees, such as the Birch, 

 the Elm, the Oak, the Holly, the Portugal and Bay laurels, the 

 Privet, the Box, will be found to send out side branches along 

 the axis from the root, or near the very root ; and the leaves of 

 these trees have little or no petiole or leaf-stalk, but begin to ex- 

 pand from nearly the very place where the leaf springs from the 

 stem. There are other trees, as the common Sycamore (the 

 Scotch Plane-tree), the Beech, the Chestnut, the Pear, the Cherry, 

 the Apple, which have a considerably long vmbranched tnmk ; 

 and the leaves of these trees will be found to have a pretty long 

 leaf-stalk." The discussion of these views further would be in- 

 compatible with our object; and we refer those who desire ad- 

 ditional information to Dr. McCosh's papers read before the 

 Botanical Society of Edinburgh, and his works on the subject. 



CoiiPosiTio-. — Leaves are divided into simj^le and compound. 

 Thus a leaf is called simple if it has only one blade {figs. 282- 

 292), however much this may be divided, so that the divisions do 

 not extend to the midrib {fig. 299), or petiole {figs. 305 and 306) ; 

 or in some cases the divisions even extend to the midrib, or 

 petiole, but the leaf is still called simple when the parts into 

 which the lamina is divided are attached by a broad base, as in 

 fig. 302. A leaf is t&cmQ(\. compound, when the midrib or petiole 



