254 THE CAUSES WHICH 



liquid, or solid form ; which the chemist, from acquaintance with 

 their laws of mutual attraction, evolves out of a glowing mass 

 into earth, air, and water. On the new-born orb, shaped by the 

 laws of relative attraction and revolution, the anatomist postu- 

 lates but the advent of a germ of physical life, whose Promethean 

 and yeast-like ignition in dead inorganic matter coiTesponds in 

 effect to electricity and magnetism, and which some think may 

 be imported by a meteorite ; and materials are at hand, accumu- 

 lated by botanist, zoologist, and surgeon, to weave the tissues of 

 species with almost unbroken thread leading up to man. 



But this speculative research, mainly accrued from the 

 destruction of objects surrounding us^ is too often undertaken 

 with the alien aim of providing for the increasing exigencies of 

 existence, rather than that of establishing physiological laws and 

 their operation, besides being totally irrespective of the globe^s 

 actual history, which remains recorded and sealed up for us in 

 the disposition of the materials constituting its surface, that 

 indicate each successive operation by which the present organic 

 arrangement has been assumed. It is on these grounds geology 

 synthetically confirms the actual formation of the earth^s varied 

 prospect by igneous and aqueous agency, and this with an 

 evidence unquestionable; comparing each old weather-worn 

 mountain and its radiating dykes with the glowing volcano and 

 lava streams of a Hecla or an ^tna, and their smoothly exca- 

 vated gullies and boulder clays, with the chilly Alpine glacier 

 and its terminal moraine heaps ; or, again, by paralleling lamellar 

 aqueous rocks and their embedded fossils with the creeping ocean 

 beds or river bottoms ; recording as measures of forgotten time 

 the present swelling and falling of the eartVs still seething 

 crust and the eroding power of all fostering heat, causing the 

 perennial lapse of streams and winds. Similar uniformity is 

 presented in the creation of the bright mantle of life which in 

 the practical theory of geology, now worked out in vai-ious parts 

 of the globe, springs into existence in progressive groups during 

 the reign of these chronic laws, harmonising with that now distri- 

 buted on the teeming globe in form, structure, and even colour 

 and evident habits of life. Here the vegetable world, dawning 

 as sea-weeds in slaty Silurian rocks, terminates with the familiar 

 twinkling forest foliage in the marls of the European Tertiary ; 



