THE RELATIONS OF GEOLOGY. 371 



mineralogy aided us more than in that of petrology, which has made 

 such marvelous strides during the past generation; but that debt of 

 obligation has been well repaid. To the petrologist is owing the dis- 

 covery of the special association of the minerals in the igneous rocks, 

 their relative order of generation, and their mutual interferences; 

 and following upon this he has made known hosts of unexpected data 

 rich in fascinating problems, opening out a new world of speculation 

 and research both for the mineralogist and for the chemist. 



GEOLOGY AND BIOLOGY. 



But if geology owes the first suggestion of the geological forma- 

 tions and their individualization to mineralogy, she has received bene- 

 fits of as long standing and of as great a moment from biolog}" and 

 biologists. The solid foundations of the paleontological side of 

 geology were laid l)y the continental biologists, ranging from Steno to 

 Cuvier, simultaneously with the discovery and the working out of the 

 order of the geological formations. Nothing in the history of the 

 growth of geology so astonished mankind or so efiectually aided in 

 lifting and dispersing the dark cloud of obloquy and neglect which 

 hid from the world the magnitude of the residts attained by the early 

 geologists as the demonstration by the biologist that the extincjt 

 organic remains collected from the geological formations were iden- 

 tical in structure with creatures living upon the earth at the present 

 day and that all these fossil forms fell naturally into a place in the 

 accepted biological classifications. At every successive stage in the 

 progress of stratigraphy since that time the geologist has been simi- 

 larly indebted to the' biologist for the interpretation and classification 

 of his fossils; and when we have respect to the rarity and to the frag- 

 mentary condition of mau}^ of these forms, we can not suflicientl}' 

 express our gratitude to biology for the aid which she has afforded us. 



But there is no need to claim that geolog}" has repaid the debt. It 

 will 1)6 enough if 1 quote here two short receipts handed in on our 

 behalf, one ])y the most distinguished biologist of the latter half of 

 the century just closed, and another by the present occupant of his 

 chair. In the words of Huxley, ""The doctrine of evolution in biology 

 is a necessary result of the logical application of the principles of the 

 geological doctrine of uniformitarianism to the phenomena of life; 

 Darwin is the natural successor of Hutton and Lyell, and the 'Origin 

 of Species' the logical sequence of the 'Principles of GeologT.''' 

 These words were written })y him about twenty 3^ears since, and his 

 successor, in reviewing from a morphological standpoint a few months 

 ago the work of zoologists accomplished (hiring these twenty years, 

 speaks as follows: 



The progress tlm High whicli -we liave passed has produced revolutionary resuhs; 

 our knowledge of facts has become materially enhanced, and our clas«itications have 



