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 



y • 

 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. 1 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 



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

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

 Modes of Research in Genetics. 



