Procreation Quotes (4 quotes)
But in my opinion we can now be assured sufficiently that no animals, however small they may be, take their origin in putrefaction, but exclusively in procreation… For seeing that animals, from the largest down to the little despised animal, the flea, have animalcules in their semen, seeing also that some of the vessels of the lungs of horses and cows consist of rings and that these rings can occur on the flea's veins, why cannot we come to the conclusion that as well as the male sperm of that large animal the horse and similar animals, and of all manner of little animals, the flea included, is furnished with animalcules (and other intestines, for I have often been astonished when I beheld the numerous vessels in a flea), why, I say should not the male sperm of the smallest animals, smaller than a flea may even the very smallest animalcules have the perfection that we find in a flea.
Letter to Robert Hooke, 12 Nov 1680. In The Collected Letters of Antoni van Leeuwenhoek (1957), Vol. 3, 329.
Every form of life can be produced by physical forces in one of two ways: either by coming into being out of formless matter, or by the modification of an already existing form by a continued process of shaping. In the latter case the cause of this modification may lie either in the influence of a dissimilar male generative matter upon the female germ, or in the influence of other powers which operate only after procreation.
From Gottfried Reinhold Treviranus, The Biology or Philosophy of Animate Nature, as quoted in translation of Ernst Heinrich Philipp August Haeckel's 8th German edition with E. Ray Lankester (ed.), The History of Creation, or, the Development of the Earth and its Inhabitants by the Action of Natural Causes (1892), 95.
The second great channel through which the impulse towards the control of procreation for the elevation of the race is entering into practical life is by the general adoption, by the educated—of methods for the prevention of conception except when conception is deliberately desired.
Studies in the Psychology of Sex (1913), Vol. 4, 588.
The theory of ramification is one of pure colligation, for it takes no account of magnitude or position; geometrical lines are used, but these have no more real bearing on the matter than those employed in genealogical tables have in explaining the laws of procreation.
From 'On Recent Discoveries in Mechanical Conversion of Motion', Proceedings of the Royal Institution of Great Britain (1873-75), 7, 179-198, reprinted in The Collected Mathematical Papers of James Joseph Sylvester: (1870-1883) (1909), Vol. 3, 23.
In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion.
(1987) -- 
