2 THE STRUGGLE FOR EXISTENCE 



animal by thoroughly objective physiological methods. As Pavlov 

 ('23) himself says, it is "the history of a physiologist's turning from 

 purely physiological questions to the domain of phenomena usually 

 termed psychical." The higher nervous activity presents such a 

 complicated system, that without special experiments it is difficult 

 to obtain an objective idea of its properties. It is known, firstly, that 

 there exist constant and unvarying reflexes or responses of the organ- 

 ism to the external world, which are considered as the especial "ele- 

 mentary tasks of the nervous system." There exist besides other 

 reflexes variable to an extreme degree which Pavlov has named 

 "conditional reflexes." With the aid of carefully arranged quantita- 

 tive experiments in which the animal was isolated in a special cham- 

 ber, all the complicating circumstances being removed, Pavlov 

 discovered the laws of the formation, preservation and extinction of 

 the conditional reflexes, which constitute the basis for an objective 

 conception of the higher nervous activity. "I am deeply, irrevocably 

 and ineradicably convinced, says Pavlov, that here, on this way lies 

 the final triumph of the human mind over its problem — a knowledge 

 of the mechanism and of the laws of human nature." 



(3) The history of the physiological sciences for the last fifty years 

 is very instructive, and it shows distinctly that in studying the 

 struggle for existence we must follow the same lines. The compli- 

 cated relationships between organisms which take place in nature 

 have as their foundation definite elementary processes of the struggle for 

 existence. Such an elementary process is that of one species devouring 

 another, or when there is a competition for a common place between a 

 small number of species in a limited microcosm. It is the object of the 

 present book to bring forward the evidence, firstly, that in studying 

 the relations between organisms in nature some investigators have 

 actually succeeded in observing such elementary processes of the 

 struggle for existence and, secondly, to present in detail the results of 

 the author's experiments in which the elementary processes have 

 been investigated in laboratory conditions. The experiments made 

 it apparent that in the simplest case we can give a clear answer to 

 Darwin's question: why has one species been victorious over another 

 in the great battle of life? 



(4) It would be incorrect to fall into an extreme and to consider 

 the complicated phenomena of the struggle for life in nature as simply 

 a sum of such elementary processes. Leaving aside the existence in 



