402 CONCLUSION. [CHAP. XV. 



important of all causes of organic change is one which is almost 

 independent of altered and perhaps suddenly altered physical con- 

 ditions, namely, the mutual relation of organism to organism, 

 the improvement of one organism entailing the improvement or 

 the extermination of others ; it follows, that the amount of organic 

 change in the fossils of consecutive formations probably serves as 

 a fair measure of the relative, though not actual lapse of time. A 

 number of species, however, keeping in a body might remain for 

 a long period unchanged, whilst within the same period, several 

 of these species by migrating into new countries and coming into 

 competition with foreign associates, might become modified ; so 

 that we must not overrate the accuracy of organic change as a 

 measure of time. 



In the future I see open fields for far more important researches. 

 Psychology will be securely based on the foundation already well 

 laid by Mr. Herbert Spencer, that of the necessary acquirement 

 of each mental power and capacity by gradation. Much light will 

 be thrown on the origin of man and his history. 



Authors of the highest eminence seem to be fully satisfied with 

 the viow that each species has been independently created. To 

 my mind it accords better with what we know of the laws im- 

 pressed on matter by the Creator, that the production and ex- 

 tinction of the past and present inhabitants of the world should 

 have been due to secondary causes, like those determining the 

 birth and death of the individual. When I view all beings not as 

 special creations, but as the lineal descendants of some few beings 

 which, lived long before the first bed of the Cambrian system was 

 deposited, they seem to me to become ennobled. Judging from 

 the past, we may safely infer that not one living species will transmit 

 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 in each genus, 

 and all the species in many genera, have left no descendants, but 

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

 glance into futurity as to foretell that it will be the common and 

 widely-spread species, belonging to the larger and dominant 

 groups within each class, which will ultimately prevail and pro- 

 create new and dominant species. As all the living forms of life 

 are the lineal descendants of those which lived long before the 

 Cambrian epoch, we may feel certain that the ordinary succession 

 by generation 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 great length. And as natural selec- 

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

 and mental endowments will tend to progress towards perfection. 



