SECTION I 



THE NEWEST THEORIES CONCERNING EVOLUTION 



BEFORE I proceed to the exposition of my own views I must 

 briefly discuss some of those attempts to explain the evolution 

 of organisms which have been made by others in recent years, 

 namely, those of Weismann and Nageli. 



The theory of heredity introduced by Weismann under 

 the name " Continuity of the Germ-plasm," l has recently been 

 widely discussed, partly in a favourable, partly in an adverse 

 spirit. 2 



This theory seeks to explain the fact that the characters 

 of the parents are inherited to so high a degree by the 

 children, and the other fact that characters can be inherited 

 from more remote ancestors, e.g. from the grandparents, 



1 A. Weismann, Die Kontinuitat des Keimplasina als Grundlage einer 

 Theorie der Vererbung, Jena, G. Fischer, 1885. The same : Zur Frage nach 

 der Vererbung erworbener Eigenschaften, Biolog. Centralblatt, 1886, Bd. vi. 

 No. 2. 



2 E.g. Naturforscher, 1886, No. 1. Eimer, Deuischer Litteraturzeitung, 

 15th May 1886. V. v. Ebner, Ueber Vererbung, Lecture delivered to the So- 

 ciety of Physicians of Steiermark, 22d March 1886 (Betz Memorabilien, 2 Heft, 

 1886). Kolliker, Die Bedeutung der Zellkerne fur die Vorgdnge der Vererbung, 

 Zeitsch./. w. Zool. 1885 ; and Das Karyoplasma und die Vererbung, eine Kritik 

 der Weisnwnns'chen Theorie von der Kontinuitat des Keimplasma, ibid. 1886. 

 Virchow, Descendenz und Pathologic, Arch. f. patholog. Anat. Bd. ciii. Koll- 

 mann, Biolog. Centralblatt, Bd. v. 1886. Virchow, Verhandlungen der Strass- 

 burger Naturforscherversammlung, 1885, Address delivered at the second general 

 meeting of this Congress. 



