332 DAEWINISM STATED BY DARWIN HIMSELF. 



totally different efEect on the mind, and the figures are 

 at once pronounced too small. In regard to subaerial 

 denudation, Mr. CroU shows, by calculating the known 

 amount of sediment annually brought down by certain 

 rivers, relatively to their areas of drainage, that one thou- 

 sand feet of solid rock, as it became gradually disinte- 

 grated, would thus be removed from the mean level of 

 the whole area in the course of six million years. This 

 seems an astonishing result, and some considerations lead 

 to the suspicion that it may be too large, but even if 

 halved or quartered it is still very surprising. Few of 

 us, however, know what a million really means : Mr. 

 Croll gives the following illustration : take a narrow strip 

 of paper, eighty-three feet four inches in length, and 

 stretch it along the wall of a large hall ; then mark off 

 at one end the tenth of an inch. This tenth of an inch 

 will represent one hundred years, and the entire strip a 

 million years. But let it be borne in mind, in relation 

 to the subject of this work, what a hundred years implies, 

 represented as it is by a measure utterly insignificant in 

 a hall of the above dimensions. Several eminent breeders, 

 during a single lifetime, have so largely modified some of 

 the higher animals, which propagate their kind much 

 more slowly than most of the lower animals, that they 

 have formed what well deserves to be called a new sub- 

 breed. Few men have attended with due care to any one 

 strain for more than half a century, so that a hundred 

 years represents the work of two breeders in succession, 



P 270 ■^"^ ^^* ^^ ^^'^ ^^ ^^^ richest geological 

 museums, and what a paltry display we be- 

 hold ! That our collections are imperfect is admitted by 

 every one. The remark of that admirable paleontologist, 

 Edward Forbes, should never be forgotten, namely, that 



