

* 



Tetraplasy, the Law of the Four Inseparable 



Factors of Evolution 



\ 



• 



BY 



HENRY FAIRFIELD OSBORN, LL.D., Sc.D. 



RB8EARCH PROFESSOR OF ZOOLOGY IN COLUMBIA UNIVERSITY, CURATOR EMERITUS OF VERTEBRATE PALEONTOLOGY 



IN THE AMERICAN MUSEUM OF NATURAL HISTORY 







PHILADELPHIA 



1912 



