CHAPTER VIII 



PENTAMORPHOGENY, OR THE ACTIVE CAUSES 

 OF ORGANIC EVOLUTION* 



From the time when Buffon and Lamarck first pointed out 

 the fallacies of "special creation" as an explanation for the 

 origin of living bodies, many master minds, aided by willing 

 contributors, have built up the great principles of organic 

 evolution on an imperishable basis. In accepting their verified 

 results as practically tested by his o\\ii experience, the writer 

 stated (7i;54) nearly two years ago (1909) that "heredity 

 upbuilds, struggle for existence stimulates, environment carves 

 and chisels, reproduction blends and continues, selective sur- 

 vival sits as the final arbiter of life or death for the individual 

 and at length for the species." But the writer further con- 

 cluded: "Speaking for himself the writer would say that this 

 one factor, 'environment,' greatly outweighs all of the others 

 in imjjortance, and that possibly it is capable of further and 

 wide extension to a degree that even the Neo-Lamarckian 

 does not go." The above "factors of organic evolution" will 

 now be considered, while a "further and wide extension" of 

 environal relation will be dwelt upon, as a great law of organic 

 progress, that we propose to designate the law of proenvironinent. 



* Since the above was written Osborn's able paper on "Tetraplasy, the 

 Law of the four inseparable factors of Evolution" has appeared in the "Journal 

 of the Academy of Natural Sciences of Philadelphia" (S. 2, Vol. 15, 1912). 

 The very thorough exposition there given of evolutionary factors and of their 

 minor branches should be carefully studied by all. The four factors which 

 Osborn accepts are Heredity, Ontogeny, Environment, and Selection. In 

 the present chapter the writer differs from Osborn in regarding Ontogeny not 

 as a cause or factor, but as a cumulated effect that results from the interaction 

 of all the factors or causes. The writer also regards Reproduction as a highly 

 complicated factor, while he presents the Law of Proenvironment as a new 

 factor of prime importance. 



So the writer would regard "Pentamorphogeny" or the cooperative action 

 of Heredity, Environment, Proenvironment, Selection, and Reproduction as 

 the combined cause by which the typical structure of any organism is effected 

 or built up. 



174 



