TRANSACTIONS OF THE SECTIONS. 187 



These conceptions of the relations of animal and vegetable forms to the earth 

 in its successive stages- lead to views of the significance of type (i. e. the general 

 system of structm-e running through various groups of organized beings) very 

 different from those under -which it -was held to be an indication of some occult 

 power dii-ectiug the successive appearance of li\'iug creatm-es on the earth. In the 

 light of evolution, type is nothmg more than the direction given to the actual 

 development of life by the sm-foce-conditions of the earth, which have supplied the 

 forces that controlled the course of the successive generations leading from the past 

 to the present. There is no indication of any inherent or pre-arranged disposition 

 towards the development of life in any particular direction. It would rather 

 appear that the actual face of natin-e is the result of a succession of apparently 

 trivial incidents,which by some very slight alteration of local circimistances might 

 often, it would seem, have been tm-ned in a difterent direction. Some otherwise 

 unimportant difference in the constitution or sequence of the substrata at any 

 locality might have determined the elevation of mountains where a hollow filled 

 by the sea was actually formed, and thereby the whole of the climatal and other 

 conditions of a large area would have been changed, and an entirely different 

 impulse given to the development of life locally, which might have impressed a 

 now character on the whole face of nature. 



But further, all that we see or know to have existed upon the earth has been 

 controlled to its most minute details by the original constitution of the matter 

 which was dra-wn together to form oiu- planet. The actual character of all in- 

 organic substances, as of all living creatm-es, is only consistent witli the actual 

 constitution and proportions of the various substances of which the earth is com- 

 posed. Other proportions than the actual ones in the constituents of the atmo- 

 sphere would have required an entirely different organization in all air-breathing 

 animals, and probably in all plants. With any considerable difference in the quan- 

 tity of water either in the sea or distributed as vapour, vast changes in the consti- 

 tution of living creatures must have been involved. Without oxygen, hydrogen, 

 nitrogen, or carbon, what we term life would have been impossible. But such 

 .speculations need not be extended. 



The substances of wliich the earth is now composed are identical with those of 

 which it has always been made up ; so far as is known it has lost nothing and has 

 gained nothing, except what has been added in extremely minute quantities by the 

 fall of meteorites. All that is or ever has been upon the earth is part of the earth, 

 has sprung from the earth, is sustained by the earth, and returns to the earth ; taking 

 back thither what it withdrew, making good the materials on which life depends, 

 without which it would cease, and which are destined again to enter into new forms, 

 and contribute to the ever onward flow of the great current of existence. 



The progress of knowledge has removed all doubt as to the relation in which the 

 human race stands to this great stream of life. It is now established that man 

 existed on the earth at a period vastly anterior to any of which we have records in 

 history or otherwise. He was the contemporary of many extinct mammalia at a 

 time when the outlines of laud and sea, and the conditions of climate over large 

 parts of the earth, were wholly difterent from what they now are, and our race has 

 been advancing towards its present condition during a series of ages for the extent 

 of which ordinary conceptions of time afford no suitable measure. These facts 

 have, in recent years, given a difterent direction to opinion as to the manner in 

 which the great groups of mauldnd have become distributed over the areas where 

 thej"^ are now found ; and difficulties once considered insuperable become soluble 

 when regarded in couuexion with those great alterations of the outlines of land 

 and sea which ai'e shown to have beeu going on up to the very latest geological 

 periods. The ancient monuments of Egypt, which take us back perhaps 7000 

 years from the present time, indicate that when they were erected the neighboiuing 

 countries were in a condition of civilization not very greatly difterent from that 

 which existed when they fell imder the dominion of the Romans or Mahometans 

 hardlj' 1500 years ago ; and the progress of the population towards that condition 

 can hardly be accounted for otherwise than by prolonged gradual transformations 

 going back to times so far distant as to require a geological rather than an histori- 



cal standard of reckoning, 



14* 



