48 



Repetition of these by Romanes. 

 Experiments on plants, Hoffmann, Car- 



RIERE, BUCKMAN. 



b. Evidence against the inheritance of acquired char- 

 acters. 



(i) Indirect evidence. 



Theoretical difficulties in the way of inher- 

 itance of acquired characters. 



(2) Direct evidence. 



Migration of germ-cells. 



Early differentiation of germ-cells. 



(3) Experimental evidence. 



Negative results obtained by Romanes. 



Graft-hybridization. 



Transplantation of ovaries. 



Transfusion of blood. 



Transplantation of ova, Heape and Buck- 

 ley. 



Amputations, Weismann. 



c. Summary. 



Small amount of evidence in affirmative. 



Inheritance of acquired characters involves a theory 

 of pangenesis. 



viii. Cofistttntional Tendency. 



(MiVART, Genesis of Species ; Hyatt, Genesis of the Arietidae, 

 Smithsonian Contriljutions, 673, 1889; Hyatt, Bioplastology 

 and the Related branches of liiologic Research, I'roc. l^oston 

 Society Natural History, Vol. 26, pp. 59-124 ; Weismann, Ger- 

 minal Selection.) 



Innate tendency, Mivart. 

 Perfecting principle, Nacem. 



