I'SSSchT^Sa Royal Microscopical Society. 167 
part, brought into close relationship with the true netted and the 
feather -veined leaf. 
From the foregoing paper the following inferences will, I trust, 
be considered as legitimate : — 
1. That, while a leaf may be considered and described, with 
respect to its vernation, internal structure, figure, articulation, in- 
sertion, margin, surface, venation, direction, colour, texture, and 
size, yet that the internal structure, so far as relates to its form, is 
to be found in the distribution of its veins. 
2. That there is a certain uniformity and simplicity in the 
formation of a leaf, which is consonant with that pervading all 
vegetable structures. 
3. That this manifests itself in the existence of an organism 
having all the semblance and parts of a real leaf, to which, for 
descriptive purposes, I have ventured to give the name of typical 
leaflet, and which, by constant repetition, forms in the aggregate 
the entire leaf. . 
4. That the leaflets in many compound leaves are essentially 
simple in their structure, not capable of being resolved into smaller 
ones. They constitute in themselves, therefore, the typical leaflets 
of which such compound leaves are composed. 
5. That while the typical leaflet often exists in a free, uncom- 
bined state in compound leaves (in Conium), yet that sometimes a 
number of them are aggregated together into one leaflet (in Hera- 
cleum ; Pastin aca) . 
6. That the venation in a typical leaflet is like the ordinary 
venation in the leaflets of compound leaves, i. e. netted or feather- 
veined. 
7. That, whatever be the shape or size of the typical leaflet, its 
venation is always the same in the same leaf; and, therefore, to 
know this of one, is equivalent to knowing that of the whole leaf. 
8. That, with respect to their form (and it is from this aspect 
alone that they are now being considered), compound leaves are 
the representatives or types of simple lobed leaves ; and, but for the 
separation of their leaflets, would almost exactly resemble simple 
lobed leaves. 
9. Til at if the leaflets in compound leaves were united at their 
edges, therefore, a simple lobed leaf would result. 
10. That the union of two or more leaflets into one is seen to 
be possible, because it is actually effected in metamorphosed leaves. 
11. That when the junction of leaflets takes place in metamor- 
phosed leaves, it is accompanied by certain modifications in the size, 
number, and course of the veins, in that part where the union is 
efi'ected ; while the rest of the veins retain their normal size, number, 
and direction, unaltered by anastomosis. 
12. That precisely the same modifications in venation are to be 
