THE ORIGIN AND DEVELOPMENT OF PLANT AND 

 ANIMAL INSTINCTS. 



A Theory of Evolution in which Life is the Central Agent. 



By Lyman C. Wooster, State Normal School, Emporia. 



^T^HE study of the origin and development of plant and animal 

 -*- instincts is inseparable from the larger study of the origin 

 and development of the plant and animal kingdoms; that is, of their 

 evolution. After fifty years of searching investigation of all phases 

 of the doctrine of evolution of plants and animals, most naturalists 

 are agreed that the evolutionist must solve four problems before he 

 can claim that his theory is fully established. These problems are: 

 variation, heredity, natural selection or adjustment to environment 

 made from without through the destruction of the less fit, and seg- 

 regation, or speciation, brought about through the separation of 

 varieties by some natural barrier that prevents their mixing. 



The potency of natural selection in cutting out the ill-adapted 

 has been so abundantly demonstrated by Darwin, Wallace and 

 others that many, for a time, thought that the solution of this 

 problem carried with it the solution of the other three problems, 

 and therefore established the doctrine of evolution of plant and 

 animal life. This is now known to be an error, though many still 

 cling to it. 



Speciation by segregation has likewise been abundantly proved 

 in this country by David Starr Jordan, O. F. Cook, C. H. Merriam, 

 J. A. Allen, A. E. Ortman and others, and by many biologists across 

 the Atlantic. This, the fourth problem, may therefore be laid aside 

 as solved. Hugo de Vries, of Amsterdam, however, claims to have 

 found another method of speciation, that of mutation, according to 

 which a species is believed to spring into existence fully formed, 

 but, as this method involves a freak or sport in variation and he- 

 redity, mutation must be referred to problems one and two. 



The first and second problems, variation and heredity, still re- 

 main among the questions that persistently plague the naturalists. 

 Outside influences and inner tendencies are respectively appealed 

 to by opposing schools of biologists to account for variation ; and 

 heredity in its essence is acknowledged by all biologists to be in 

 some measure a mystery, 



(227) 



