138 PROGRESS OF SCIENCE. 



descended by gradual modification from one primal form, 

 commanded greater influence still, because he systematised 

 a large number of facts, and brought in the idea that law 

 governed the living world as it governed all else. Later, 

 William Smith pointed out that rocks were deposited in 

 successive order, and thus carried the doctrine of evolution 

 into the domain of geology ; and, subsequently, Lyell sub- 

 stantiated the theory as regards the main problems involved in 

 the formation of the earth. In astronomy, as early as 1744 

 and 1/99, tne same lesson was taught by Kant and Laplace, 

 regarding the origin, constitution, order, and gradual formation 

 of the heavenly bodies. Thus far, we see that the evolutionary 

 law was demonstrated as having obtained in astronomy and 

 geology, and that it had been all but demonstrated in 

 biology. To this last determination without speaking of 

 Von Buch, Lecoq, Von Baer, and Dean Herbert, each of 

 whom did valuable work three men, Malthus, Dr. Wells, 

 Patrick Matthew, contributed an important share. Malthus 

 (1798) pointed out the struggle for existence which keeps 

 human reproduction to the same limit as food-supply; Dr. 

 Wells (1813) actually hit upon the notion of " natural 

 selection " as regards the races of mankind ; Patrick Matthew 

 (1831) went even further: he not only intimated the same 

 idea, but he applied it to the whole of nature. We thus see 

 that the staircase of biological evolution had been gradually 

 ascended before Charles Darwin reached its upper platform. 

 This is not all. Herbert Spencer, as early as 1852, had 

 published his " Development Hypothesis/' which embraced 

 the main arguments, features, and facts of the whole evolu- 

 tionary doctrine, and enunciated, with luminous force, the 

 doctrine of descent with modification. 



It seems, after such a recapitulation, as if there remained 

 nothing for Darwin to do : the evolutionary theory had been 

 strongly established in several branches, and had been fairly 

 sketched even in biology. Yet, for all that, there was a 

 vacant place left, and that vacant place was the most im- 

 portant of all. It was absolutely imperative, before biological 

 evolution could be accepted, that it should be demonstrated 

 beyond doubt by a vast array of proofs of all kinds. This 



