9± Charles Schuchert— Historical Geology, 1818-1918. 



Gray says in part : 



"The gist of Mr. Darwin's work is to show that such varieties 

 are gradually diverged into species and genera through natural 

 selection; that natural selection is the inevitable result of the 

 struggle for existence which all living things are engaged in; 

 and that this struggle is an unavoidable consequence of several 

 natural causes, but mainly of the high rate at which all organic 

 beings tend to increase. 



Darwin is confident that intermediate forms must have 

 existed; that in the olden times when the genera, the families 

 and the orders diverged from their parent stocks, gradations 

 existed as fine as those which now connect closely related species 

 with varieties. But they have passed and left no sign. The 

 geological record, even if all displayed to view, is a book from 

 which not only many pages, but even whole alternate chapters 

 have been lost out, or rather which were never printed from the 

 autographs of nature. The record was actually made in fossil 

 lithography only at certain times and under certain conditions 

 (i. e., at periods of slow subsidence and places of abundant sedi- 

 ment) ; and of these records all but the last volume is out of 

 print; and of its pages only local glimpses have been obtained. 

 Geologists, except Lyell, will object to this, — some of them 

 moderately, others with vehemence. Mr. Darwin himself admits, 

 with a candor rarely displayed on such occasions, that he should 

 have expected more geological evidence of transition than he 

 finds, and that all the most eminent paleontologists maintain the 

 immutability of species. 



The general fact, however, that the fossil fauna of each period 

 as a whole is nearly intermediate in character between the 

 preceding and the succeeding faunas, is much relied on. "We 

 are brought one step nearer to the desired inference by the similar 

 'fact,' insisted on by all paleontologists, that fossils from two 

 consecutive formations are far more closely related to each other, 

 than are the fossils of two remote formations. 



It is well said that all organic beings have been formed on two 

 great laws ; Unity of type, and Adaptation to the conditions of 

 existence . . . Mr. Darwin harmonizes and explains them 

 naturally. Adaptation to the conditions of existence is the 

 result of Natural Selection ; Unity of type, of unity of descent. ' ' 



Gray's article was soon followed by another one from 

 Agassiz on Individuality and Specific Differences among 

 Acalephs, but the running title is "Prof. Agassiz on the 

 Origin of Species" (30, 142, 1860). Agassiz stoutly 

 maintains his well known views, and concludes as 

 follows : 



