SSg ScTriSl] Royal Microscopical Society. 169 
22. That the notion of a leaf being imperfectly developed, be- 
cause it is divided by deep recesses, is untenable. 
23. That to suppose a leaf to be perfect only when it has all its 
parts filled in to the very margin by parenchyma, is to assume that 
all leaves should be thus developed conformably with some assumed 
geometric figure, which, if carried into effect, would reduce them, 
one and all, to a monotonous series of ellipses, ovates, or some other 
figure, which it may be fairly presumed to be difiicult to describe. 
24. That the form of a leaf is perfect as a leaf, and not as some 
geometric figure yet to be assigned to it, A Fennel leaf is perfect in 
form with nothing but its linear segments ; so is that of Lilac, which 
has no segments at all. 
25. That the projection in form of a leaf accords with that of 
its component leaflets. When these have ceased to grow, the leaf 
has arrived at its stage of maturity. It is then that it becomes 
stamped with its normal form, by which it is characterized from 
other leaves. Its character depends on that of all its parts ; and it 
derives its beauty from their assemblage, without being like one of 
them. The human figure is bounded by a series of ellipses — the 
whole figure is not an ellipse. 
26. That each typical leaflet contains within itself the distri- 
bution of every small vein and minute veinlet, to its ultimate 
destination in the parenchyma. To have become conversant, there- 
fore, with the anatomy of this portion of a leaf, is to have become 
acquainted with the internal structure of the entire leaf, inasmuch 
as the whole is made up of similar parts. 
27. and finally. The only legitimate limit which can be put on 
such a subdivision of an entire leaf is that when all trace of a real 
typical leaflet, to be discovered within its structure, ceases. 
