A Demonstration of the Origin of Species by Natural Selection

PROVED FACTS	NECESSARY CONSEQUENCES (afterwards taken as Proved Facts).
Rapid Increase of Organisms, pp. 29, 265; (“Origin of Species,” p. 75, 5th Ed.)	Struggle for Existence, the deaths equalling the births on the average, p. 30; (“Origin of Species,” chap. III.)
Total Number of Individuals Stationary, pp. 30, 266.
Struggle for Existence.	Survival of the Fittest, or Natural Selection; meaning simply, that on the whole those die who are least fitted to maintain their existence; (“Origin of Species,” chap. IV.)
Heredity With Variation, or general likeness with individual differences of parents and offspring, pp. 266, 287-291, 308; (“Origin of Species,” chap. I., II., V.)
Survival of the Fittest.	Changes of Organic Forms, to keep them in harmony with the Changed Conditions; and as the changes of conditions are permanent changes, in the sense of not reverting back to identical previous conditions, the changes of organic forms must be in the same sense permanent, and thus originate Species.
Change of External Conditions, universal and unceasing.—See “Lyell’s Principles of Geology.”