THE HAMILTON ASSOCIATION. 23 



that the organism and the conditions in which it exists in nature are 

 perfectly adapted, the one to the other. Now we are credibly in- 

 formed that the conditions of the earth's surface were quite different 

 in some of the periods of the world's history to what they are now ; 

 so the life of these periods would therefore have been quite un- 

 suited to the present conditions^ just as the life of the present is 

 wholly unfit for the past conditions. So then we infer that life ap- 

 peared on this globe at such times as the conditions were ready to 

 receive it, and in such forms as were suited to these conditions. 

 Every form of life in the past being as perfectly adapted to its re- 

 quirements, and as thoroughly in harmony with its environment as 

 that of the present. Now the present diverse conditions of the 

 globe's surface are as nothing compared with what the past condi- 

 tions were, with what they are at the present ; therefore the disclos- 

 ures of geology, that the forms of the life of the past were so differ- 

 ent from those of the present, is the natural and necessary result of 

 the vastly different conditions in which they lived. 



The idea entertained by many, that at every change of the 

 earth's conditions the previous forms were wholly swept away, and 

 an entirely new set introduced, is contrary to the evidence and op- 

 posed to the requirements of the case. That new forms appeared 

 on the scene long after others had been introduced, is quite evident, 

 that they appeared conspicuously, and even suddenly, seems to be 

 indicated, but that they also appeared whilst some at least of the 

 previously existing forms were still there, seems to be satisfactorily 

 demonstrated. The geological record clearly indicates that there 

 has been no break in the stream of life from its first introduction to 

 the present, but a steady, progressive continuity. Geologists inform 

 us that they recognize some of the very earliest forms of life to be 

 found in the rocks, as still living at the present day. Is it at all un- 

 likely that there may be many more of the descendants of early 

 forms still living that they do not recognize? We know that some 

 of the species of the present can change their location /and accom- 

 modate themselves to altered conditions, and are modified thereby. 

 May not many of the forms of life of the past periods in the world's 

 changing conditions have succeeded in accommodating themselves 

 to these changes, and been themselves so changed by them, bringing 

 them into harmony with their surroundings, as to make it impossi- 

 ble now to recognize them ? The probability is, there is not a 



