Chap. XIV. CONCLUSION. 489 



first bed of the Silurian system was deposited, they seem 

 to me to become ennobled. Judging from the past, we 

 may safely infer that not one living species will trans- 

 mit its unaltered likeness to a distant futurity. And of 

 the species now living very few will transmit progeny 

 of any kind to a far distant futurity ; for the manner in 

 which all organic beings are grouped, shows that the 

 greater number of species of each genus, and all the 

 species of many genera, have left no descendants, but 

 have become "utterly extinct. We can so far take a 

 prophetic glance into futurity as to foretel that it will 

 be the common and widely-spread species, belonging to 

 the larger and dominant groups, which will ultimately 

 prevail and procreate new and dominant species. As 

 all the living forms of life are the lineal descendants of 

 those which lived long before the Silurian epoch, we 

 may feel certain that the ordinary succession by genera- 

 tion has never once been broken, and that no cataclysm 

 has desolated the whole world. Hence we may look 

 with some confidence to a secure future of equally in- 

 appreciable length. And as natural selection works 

 solely by and for the good of each being, all corporeal 

 and mental endowments will tend to progress towards 

 perfection. 



It is interesting to contemplate an entangled bank, 

 clothed with many plants of many kinds, with birds 

 singing on the bushes, with various insects flitting about, 

 and with worms crawling through the damp earth, and 

 to reflect that these elaborately constructed forms, so 

 different from each other, and dependent on each other 

 in so complex a manner, have all been produced by 

 laws acting around us. These laws, taken in the largest 

 sense, being Growth with Reproduction; Inheritance 

 which is almost implied by reproduction ; Variability 

 from the indirect and direct action of the external con- 



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