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A) The believers in the Derivative origin of species hold that new species have gradually been produced in the course of millions of years by the Law of Inheritance, or the well known breeder's principle that like produces like. As a general rule any remarkable variation in a given species is eliminated by intercrossing with normal individuals, but in particular cases, such [[insertion]] ^ for example [[/insertion]] as those where the variation affords any peculiar advantage to the individual, [[insertion]] ^ or where individuals are isolated [[strikethrough]] from others [[/strikethrough]] by any means from their fellows, [[/insertion]] it is propagated & from generation to generation exaggerated by the same great Law of Inheritance. In other words, [[insertion]] ^ the Law of [[/insertion]] Inheritance, as a general rule keeps species [[insertion]] ^ to one invariable standard [[/insertion]] [[strikethrough]]] from varying [[/strikethrough]], but in particular cases it causes them to deviate from it. But, says Agassiz, "this statement itself implies a contradiction, for it assumes that the same influences prevent & produce changes in the condition of the Animal Kingdom." (Meth. St. p.281) So that if any one says that the wind sometimes melts ice & sometimes prevents it from melting, "the statement implies a contradiction, for it assumes that the same influences prevent & produce changes." And if another man says that the action of insectivorous insects upon plant-feeding insects tends, as a general rule, to keep them within due limits, but in exceptional cases causes them to become exorbitantly numerous, this statement also "implies a contradiction", because it assumes that the same causes sometimes produce different effects. 

Because it has been satisfactorily, & certainly most beautifully, demonstrated by Agassiz that certain coral-making Radiata have not varied [[insertion]] ^ from the normal type [[/insertion]] in the last 70,000 years, it by no means follows that all other species in the Animal Kingdom have been equally invariable in all time. As well might we argue that because certain butterflies are notoriously constant in their coloration, therefore all other species of butterflies are equally constant. Whereas we know that in certain species it is difficult to find two individuals exactly alike. 

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Transcription Notes:
Louis Agassiz