THE STUDY OF SOCIOLOGY. 725 



those set forth long .afterward by Werner, we come to Hutton, with 

 whom in fact rational geology commences. For the untenable Nep- 

 tunist hypothesis, asserting a once-universal aqueous action unlike the 

 present, Hutton substituted an aqueous action, marine and fluviatile, 

 continuously operating as we now see it, antagonized by a periodic 

 igneous action : he recognized denudation as producing mountains 

 and valleys ; he denied so-called primitive rocks ; he asserted meta- 

 morphism ; he taught the meaning of unconformity. Since his day 

 rapid advances in the same direction had been made. "William Smith, 

 by establishing the order of superposition of strata throughout England, 

 prepared the way for positive generalizations ; and, by showing that 

 contained fossils are better tests of correspondence among strata than 

 mineral characters, laid the basis for subsequent classifications. The 

 better data thus obtained, theory quickly turned to account. In his 

 " Principles of Geology," Lyell elaborately worked out the uniformi- 

 tarian doctrine the doctrine that the earth's crust has been brought 

 to its present complex structure by the continuous operation of forces 

 like those we see still at work. More recently, Prof. Ramsay's theory 

 of lake-formation by glaciers has helped in the interpretation ; and by 

 him, as well as by Prof. Huxley, much has been done toward elucidat- 

 ing past distributions of continents and oceans. Nor must we forget 

 Mallet's " Theory of Earthquakes " the only scientific explanation of 

 them yet given. And there must be added another fact of moment. 

 Criticism has done far more here than abroad, toward overthrowing 

 the crude hypothesis of universal "systems" of strata, which suc- 

 ceeded the still cruder hypothesis of universal strata, enunciated by 

 Werner. 



That our contributions to Biological Science have in these later 

 times not been unimportant, may, I think, be also maintained. Just 

 noting that the " natural system " of plant-classification, though French 

 by development, is English by. origin, since Ray made its first great 

 division, and sketched out some of its subdivisions, we come, among 

 English botanists, to Brown. He made a series of investigations in 

 the morphology, classification, and distribution of plants, which in 

 number and importance have never been equalled: the "Prodromus 

 Flora? Nova>Hollandia " is the greatest achievement in classification 

 since Jussieu's " Natural Orders." Brown, too, it was who solved the 

 mystery of plant-fertilization. Again, there is the conception that 

 existing plant-distribution has been determined by past geological 

 and physical changes a conception we owe to Dr. Hooker, who has 

 given lis sundry wide interpretations in pursuance of it. In Animal- 

 physiology there is Sir Charles Bell's discovery respecting the sensory 

 and motor functions of the nerve-roots in the spinal cord ; and this 

 tmderlies multitudinous interpretations of organic phenomena. More 

 recently we have had Mr. Darwin's great addition to biological 

 science. Following in the steps of his grandfather, who had a'nti- 



