SECTIOX I 



THE NEWEST THEORIES CONCEENIXG 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,"^ has recently been 

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

 spirit.^ 



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, 



^ A. Weismaun, Die Kontiiiuitdt des Keimplasma als Grundlage einer 

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

 der Vererhung erivorbener Eigenschaften, Biolog. Centrcdblatt, 1886, Bd. vi. 

 No. 2. 



- E.g. Xaturforscher, 1886, No. 1. Eimer, Deutscher LitteraturzeiUing, 

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

 ciety of Physicians of Steiermark, 22d March 1886 {Betz MemoraMUen, 2 Heft, 

 1886). Kolliker, Die Bedeutung der Zellkerne fur dAe Vorgange der Vererhung, 

 Zeitsch.f. vj. Zool. 1885 ; and Das Karyojjlasnuc vMd die Vererhung, eine Kritik 

 der WeisvwMns'cheyi Theorie von der Kontinuitdt des Keimplasma, ibid. 1886. 

 Virchow, Descendenz taid Pathologie, Arch. f. patholog. Anat. Bd. ciii. Koll- 

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

 burger Naturforscherversammlung, 1885, Address delivered at the second general 

 meetinoc of this Congress. 



