34 TEXT-BOOK OF EMBRYOLOGY. 



maturation processes of the germ cells. The fact of heredity is the resem- 

 blance between offspring and parents. From the standpoint of fertilization 

 in its relation to heredity the significant point is that the offspring may 

 develop qualities that were the individual possessions of either one parent or 

 the other. The chromatin, regarded as the heredity material, is the only 

 substance which is contributed in equal or approximately equal parts by the 

 two parents. The union of the germ cells brings the chromatin of the parents 

 together in the fertilized ovum or zygote which develops into a new individual. 

 Upon these facts rests the possibility that the offspring may inherit equally 

 from both parents. 



References for Further Study. 



BUCHNER, P.: Praktikum der Zellenlehre. Teil I, 1915. 



CONKLIN, E. G.: Heredity and Environment in the Development of Men. 3d Ed., 

 1920. 



HERTWIG, R.: Befruchtung. In Hertwig's Handbuch der vergleichenden und experi- 

 mentellen Entwickelungslehre der Wirbeltiere. Bd. I, Teil I, Kap. II, 1903. Contains 

 extensive bibliography. 



KELLICOTT, W. E.: Text-book of General Embryology. Chap. V, 1913. 



LOEB, J.: Die chemische Entwickelungserregung des thierischen Eies. 1909. 



MARSHALL, F. H. A.: The Physiology of Reproduction. 1910. 



MINOT, C. S.: The Problem of Age, Growth, Death. 1907. 



MORGAN, T. H.: Heredity and Sex. 1913. 



MORGAN, T. H.: The Physical Basis of Heredity. 1919. 



WILSON, E. B.: The Cell in Development and Inheritance. 1900. 



