GENETIC SYSTEM: RELATION TO CHARACTERISTICS 1 29 



ticular type of Y-chromosome are inherited in tlie male line 

 exclusively. 



Three Main Methods of Distribution of Inherited Char- 

 acteristics: There exist therefore three diverse systems of 

 distributing hereditary characteristics, depending respec- 

 tively on the X-chromosomes, the autosomes, and the Y- 

 chromosomes. In each of these the rules of inheritance are 

 given by the special method of distribution of the three 

 types of chromosomes, taken in connection with the facts 

 of dominance and recessiveness. Inheritance which follows 

 the distribution of the X-chromosomes is commonly called 

 sex-linked inheritance. That following the distribution of 

 autosomes is known as autosomal or typical Mendelian in- 

 heritance. Less important than those just named is Y- 

 chromosome inheritance. All these methods are included 

 under the term Mendelian inheritance, employed in a broad 

 sense. 



In some organisms still other methods of inheritance 

 exist; some of these will be presented in later chapters. In 

 higher animals and plants most inheritance occurs In one 

 of the three methods named in the preceding paragraph. 



NOTES AND REFERENCES ON CHAPTER V 



1. Page 106. G. Mendel (1866), Experiments in Hybridisation. 

 pp. 317-368, in Wm. Bateson's Mendel's Principles of Heredity 

 (Cambridge, 1909). 



2. Page 125. On the inheritance of horns, see the review by W. Lan- 

 dauer (1925), Ergebnisse in der Erbanalyse der Behornung von Rind, 

 Schaf und Ziege. Zeitschrift fiir Induktive Abstammungs — und Verer- 

 bungslehre, Bd. 39, pp. 294-322. 



3. Page 126. For an account of inheritance through the Y-chromo- 

 some in Lebistes, see O. Winge (1927), One-sided Alasculine and 

 Sex-linked Inheritance in Lebistes reticulatus. Journal of Genetics, 

 vol. 12, pp. 145-162. 



