"But the blindness of those who think it absurd to suppose that complex organic forms may have arisen by successive modifications out of simple ones, becomes astonishing when we remember that complex organic forms are daily being thus produced. A tree differs from a seed immeasurably in every respect--in bulk, in structure, in colour, in form, in specific gravity, in chemical composition--differs so greatly that no visible resemblance of any kind can be pointed out between them. Yet is the one changed in the course of a few years into the other--changed so gradually that at no moment can it be said, 'Now the seed ceases to be, and the tree exists.' What can be more widely contrasted than a newly-born child, and the small, semi-transparent gelatinous spherule constituting the human ovum? The infant is so complex in structure that a cyclopaedia is needed to describe its constituent parts. The germinal vesicle is so simple, that a line will contain all that can be said of it. Nevertheless, a few months suffices to develop the one out of the other, and that too by a series of modifications so small, that were the embryo examined at successive minutes, not even a microscope would disclose any sensible changes. That the uneducated and ill-educated should think the hypothesis that all races of beings, man inclusive, may in process of time have been evolved from the simplest monad a ludicrous one is not to be wondered at. But for the physiologist, who knows that every individual being _is_ so evolved--who knows further that in their earliest condition the germs of all plants and animals whatsoever are so similar, 'that there is no appreciable distinction among them which would enable it to be determined whether a particular molecule is the germ of a conferva or of an oak, of a zoophyte or of a man'[332]--for him to make a difficulty of the matter is inexcusable. Surely, if a single structureless cell may, when subjected to certain influences, become a man in the space of twenty years, there is nothing absurd in the hypothesis that under certain other influences a cell may, in the course of millions of years, give origin to the human race. The two processes are generically the same, and differ only in length and complexity." * * * * * The very important extract from Professor Hering's lecture should perhaps have been placed here. The reader will, however, find it on page 199. FOOTNOTES: [321] 'Origin of Species,' Hist. Sketch, p. xvi. [322] See 'Naval Timber and Arboriculture,' by Patrick Matthew, published by Adam and C. Black, Edinburgh, and Longmans and Co., London, 1831, pp. 364, 365, 381-388, and also 106-108, 'Gardeners' Chronicle,' April 7, 1860. [323] 'Vie et Doctrine Scientifique de Geoffroy Etienne St. Hilaire,' Paris, Strasbourg, 1847, pp. 344-346. [324] 'Hist. Nat. Gen.,' tom. ii. 413. [325] 'Hist. Nat. Gen.,' tom. ii. p. 415. [326] Ibid. [327] Ibid. p. 421. [328] 'Hist. Nat. Gen.,' vol. ii. p. 431, 1859.