THE FOUR INSEPARABLE FACTORS OF EVOLUTION. 



285 



I. 



Inorganic 



II. 



Organic 



A. Physical Con 



DITIONS 1 



B. Food and C. With Individuals of 



Nutrition 



the Same Kind 2 



Examples. 



D. With Ind 



other Kinds, Species, 1 

 Varieties, Genera, 

 Etc. 



Physical conditions. Nature of 

 Chemical conditions. Chemical con- 



i. e. f relations of parentage, Favorable 



Temperature. 



Heat. 



Cold. 



Moisture. 



Composition of water. 



Composition of atmos- 

 phere. 



stitution of 



of offspring, of various 

 degrees of blood relation- 

 ship, sexual and repro- 

 ductive relationships, of 

 similar sports, muta- 

 tions, varieties, species, 

 etc. 



Cooperative 

 Friendly 



Commensal 



Symbiotic 



Parasitic 



Unfavorable 

 Hostile 



Competitive 

 Destructive 

 Parasitic 



Some writers have grouped these relations with individuals of the same kind 

 and with individuals of other kinds under selection, using that term in a too 

 comprehensive sense, as including, for example, individual choice of environment, 

 which is evidently not one of the modes of selection in the strict Darwinian sense. 



The environment may migrate around an organism, as in the course of 

 geologic change, while the organism may through force of circumstances migrate 

 into a new environment. All the relations with (C) individuals of the same kind 



with (D) individuals of other kinds may result in bringing organisms into a 



change of environment 



This is especially true of animals in which psychic segre 



gation, isolation, tradition, and imitation bring about changes of environment 



2. Ontogeny. 3 



Ontogeny is the visible expression of heredity as reacting to environment 

 and selection. It includes all the phenomena of change in the individual develop- 

 ment of organisms as a whole and in their parts. Ontogeny thus strictly begins 

 with the fertilized ovum and includes all the internal changes in the life cycle, all 

 somatic or somatogenic as distinguished from blastic or blastogenic conditions, 



all 



quired 



or 



(i 



or 



'nature" conditions 

 Rcid 



4 



nurture ' conditions as distinguished from "inborn" 

 In a sense, as has recently been pointed out by Archdall 



discussion with Lankester, all characters are acquired 



i 



or separation by water. 



gregation 



As partly connected with segregation of kind, isolation of kind, consciousness of kind, traditions 

 d, imitations of kind, etc. 



•Osborn, H. F.: The Cartwright Lectures for 1892 before the Alumni of the College of Physi- 

 cians and Surgeons, New York.— Present Problems in Evolution and Heredity. 1. The Contem- 

 porary Evolution of Man. 2. Difficulties in the Heredity Theory. 3. Heredity and the Germ 

 tells. N. Y. Medical Record, vol. 20, Mar. 5 and April 23, 1892. Alte und Neue Problcme der 

 nylogenese, Sep. Abdr. aus d. Ergebnisse der Anatomic und Entwickclungsgeschichte (von Fr. Merkel 

 u. R. Bonnet, Gottingen), Band III, 1893, pp. 584-619. 



. . . Obviously, all characters depend equally on an interaction between germinal potenti- 

 ality and external stimulus. They are all, therefore, as inborn and acquired, as blastogenic and 

 omatogemc as they can possibly be. No such things are conceivable as purely blastogenic and 



omatogemc characters, or characters which are more blastogenic or somatogenic than others." 

 nature. vn\ so m~ ooh * . .—« ° 



