1865. Gregor Mendel publishes the results of experi- 



ments in crossing strains of garden peas and 

 enunciates the laws of hybridization. 



1866. Haeckel in his Generelle Morphologic emphasizes 



the material continuity of 'offspring and 

 parent. 



1869. Darwin in Variation of Animals and Plants 



under Domestication puts forward the hy- 

 pothesis of pangenesis. 



1875. Hertwig determines that fertilization results 



from the union of one egg and 07ie sperm. 



1880-1. Francis Balfour publishes his Comparative Em- 

 bryology. 



1883, Francis Galton uses the term Eugenics in In- 



quiries into Human Faculties. 

 — — Van Beneden and Boveri discover chromosomes. 



Van Beneden shows that every nucleus may 



contain nuclear substance obtained from each 

 . parent, and that a reduction in the number of 

 chromosomes occurs in maturation. 



1884. Carl Nageli presents his Mechanico-physiologi- 



cal Theory of Evolution. 

 1889. Hugo DeVries puts forward the theory of Pan- 



gens or "Intracellular Pangenesis." 



Galton in Natural Inheritance enunciates the 



Laws of Ancestral Inheritance. 



1891. Henking finds two kinds of spermatozoa in 



Pyrrhocoris. 



1893. Weismann publishes his Germ Plasm Theory. 



1895. Eimer proposes his Orthogenetic Theory of Evol- 



lution. 



1896. E. B. Wilson publishes The Cell in Develop- 



ment and Inheritance. 



1900. Re-discovery of Mendel's publication (1865) 



and the publication of similar investigations 

 by Bateson, DeVries, Correns and Tscher- 

 mak. 



1901. DeVries publishes ''Die Mutations Theorie." 



McClung finds a numerical difference in the 



chromosomes in the spermatozoa of the grass- 

 hopper. 



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