While, therefore, teratology may be an unsafe guide in strictly artificial schemes, it is obvious that its teachings should have great weight in all philosophical systems of classification.
The questions will constantly arise, does such and such a form represent the ancestral condition of certain plants? Is it a reversion to that form? or is it, on the other hand, the starting point of new forms?
Such questions cannot receive at present any satisfactory answer, but the evidence we have seems to indicate that pre-existing forms were simpler, and less specialised in structure than those now existing, and hence if we meet with malformations of a simple kind, we may consider them as possible reversions; while, if they present features of increased complexity, and more sharply defined differentiation, we may assume them to be evidences of a progressive rather than of a retrogressive tendency.
That monstrosities so called may become the starting points of new forms is proved by circumstance that, in many cases, the peculiarities are inherited so that a new "race" is produced and perpetuated: and if a new race, why not a new species? The difference is one of degree only.
FOOTNOTES:
[553] See Clos., 'Bull. Soc. Bot. Fr.,' 1856, vol. iii, p. 679.
[554] 'Théorie de la Feuille,' p. 26.
[555] An additional illustration of this may be cited, which has been brought under the notice of the writer by Dr. Welwitsch recently, and in which some of the leaflets of the pinnate leaf of a species of Macrolobium were absent, and their place supplied by flowers arranged in cymes.
[556] The presence of a bud at the extremity once considered to be an absolute distinction between branch and leaf, which latter never forms a bud exactly at the apex—is invalidated by the case of the Nepaul barley, p. 174.