MISCELLANEOUS PAPERS. 383 



that there is present in every organism a self which preserves its iden- 

 tity through all the successive stages of progressive psychical experi- 

 ence, and acts as a unifying principle in coordinating all the several 

 stages of development within the sphere of permanent personality. 



All in every-day experience agree that it is futile to attempt to ex- 

 press life values in terms of mathematical units. No one would try 

 to sell ideas to the publishers by the pound, nor to express the skill 

 of an engineer by the yard unit, nor to extract the cube root of a the- 

 ory in science. Then why should a biologist attempt to establish a 

 physical explanation for tropism, as does Doctor Loeb, a mathemat- 

 ical basis for heredity, as did Doctor Weismann and his followers in 

 their germ-plasm theory, or make heredity a problem in physics, as 

 did Mendel and DeVries in their manipulation of chromosomes in 

 the egg and sperm '? 



I maintain that the only method a biologist should use in studying 

 life processes is one that harmonizes with the method used by life 

 itself in developing its higher powers in the individual and in the 

 race. This life method has been studied by biologists along four 

 ditferent lines of research ; and the fact that these four lines of study, 

 pursued in fields so widely diverse, harmonize in their results so per- 

 fectly, is one of the chief arguments for the validity of the method. 



Four submethods for studying the plant and animal kingdoms are : 

 1. That of the systematic botanist and zoologist. 

 2 That of the evolutionist. 



3. That of the embryologist (ontogeny). 



4. That of the paleontologist (phylogeny). 



The biologist has long known that plants and animals may be 

 grouped in a tree-like ascending series, made up of branches, classes, 

 orders, genera, and species. This work of the systematist serves as a 

 standard of comparison in ranking activities. 



The evolutionist holds, as a basic principle of his theory, that life 

 has always had a general upward tendency, and consequently the later 

 and higher organisms and processes have been evolved from earlier 

 and lower organisms and processes. 



The embryologist has learned that the life of each higher organism, 

 in the course of its development from the egg, repeats in a general 

 way the history of its race. This discovery evidently harmonizes with 

 the theory of evolution. 



The paleontologist, in arranging the fossil life forms in their chron' 

 ological sequence, has found that the lower forms of life of the sys- 

 tematist appeared on earth first, and that the higher forms appeared 

 successively later. 



The systematic biologist, the evolutionist, the embryologist and the 

 paleontologist agree in concluding that life on earth, in its mode of 



