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Researches on the Foraminifera. 



[June 14, 



The passage of each individual of this species through a series of 

 forms which, in the classification of M. D'Orbigny, belong to four 

 different Orders, sufficiently proves that, among Foraminifera, plan of 

 growth is a character of secondary value ; whilst the retention, in the 

 perfected disk, of the entire series of those ancestral forms, through 

 which the very simplest of Foraminiferal organisms has become 

 evolved into one of the most complex, invests this abyssal type of 

 Orbitolites with a peculiar interest and value. 



Having been for some time engaged in the study of the large 

 collection of Orbitolites (chiefly made on the Fiji reef) brought home 

 by the " Challenger," with a view to the preparation (at the request 

 of the late Sir C. Wyville Thomson) of a complete Report upon this 

 generic type, the author has delayed the publication of this remark- 

 able confirmation of his previously- expressed views, until he should 

 have concluded his investigation of the large mass of new material 

 which has thus come into his possession having early seen reason to 

 believe that his recent study would prove of some value in its general 

 relation to the Theory of Descent. And he now offers the results of 

 it as a contribution to that great inquiry, in the conviction that (as 

 was admirably said thirty-five years ago by Sir James Paget) " the 

 highest laws of our science are expressed in the simplest terms, in the 

 lives of the lowest orders of creation." 



The aggregate of the phenomena presented by the evolutionary 

 history of this type (and equally, the author fully believes, by that of 

 every other of the more complex types of Foraminifera) may be thus 

 summed up : — 



1. That there has been a progressive specialization in the structure 

 of the shelly envelope, which, in the highest type of Orbitolites (the 

 large 0. complanata of the Calcaire Grossier and of the Fiji reefs) 

 attains a very extraordinary complexity. 



2. That this specialization has followed a very definite and well- 

 marked line. 



3. That this progressive complication in the structure of the disk 

 is attained without any corresponding specialization in the structure 

 of the animal, whose sarcodic body retains throughout (as far as the 

 most careful examination can enable us to determine) its primitive 

 homogeneousness. 



4. That all the ancestral forms through which the highest type has 

 passed, are still living and flourishing under exactly the same condi- 

 tions (so far as can be ascertained) as itself. 



The full discussion which the doctrine of the " Origin of Species 

 by Natural Selection " has now received, may be considered as 

 having clearly established that what has been called the Law of 

 Natural Selection is simply a generalised expression of the fact, that 

 among the varetal forms continually arising de novo, those survive 



