244 Mechanism of Mendelian Heredity 



consisted of a series of smaller chromosomes, each of 

 which may be a factor in the determination of a heredi- 

 tary character which is transmitted according to Men- 

 del's law of segregation. Biology has thus reached in the 

 chromosome theory of Mendelian heredity an atomistic 

 conception, according to which independent material 

 determiners for hereditary characters exist in a linear 

 arrangement in the chromosomes. 



II 



4. We are not concerned in this volume with the 

 many applications of the theory of heredity to the 

 breeding of plants, animals, and man; the reader 

 will find a discussion of these topics in the numerous 

 writings of the special workers on genetics.^ We are, 

 however, interested in the bearing this work has on 

 the conception of the organism. Two questions present 

 themselves: Is the organism nothing but a mosaic 

 of hereditary characters determined essentially by de- 

 finite elements located in the chromosomes; and if 

 this be true, what makes a harmonious whole organism 

 out of this kaleidoscopic assortment? We call it a 

 kaleidoscopic assortment since a glance at the list of 

 hereditary characters found in one chromosome, 

 according to Morgan, shows that there is apparently 



'Bateson, W., Mendel* s Principles of Heredity, 3d ed., 1913; 

 Davenport, Chas. B., Heredity in Relation to Eugenics, 191 1. Pearl, R., 

 Modes oj Research in Genetics. 



