CHAPTER IV. 



Characters as Hereditary and Acquired 



{continued). 



(c.) 



Experimental Evidence in favour of the Inheritance 

 of Acquired Characters. 



Notwithstanding the fact already noticed, that 

 no experiments have hitherto been published with 

 reference to the question of the transmission of 

 acquired characters \ there are several researches 



* The experiments of Galton and Weismann upon this subject are 

 nugatory, as will be shown later on. But since the above was written 

 an important research has been published by Mr. Cunningham, of the 

 Marine Biological Association. For a full account I must refer the 

 reader to his forthcoming paper in the Philosophical Transactions. The 

 following is his own statement of the principal results : — 



"A case which I have myself recently investigated experimentally 

 seems to me to support very strongly the theory of the inheritance of 

 acquired characters. I have shown that in normal flat-fishes, if the 

 lower side be artificially exposed to light for a long time, pigmen- 

 tation is developed on that side ; but when the exposure is commenced 

 while the specimens are still in process of metamorphosis, when 

 pigment-cells are still present on the lower side, the action of light 

 does not prevent the disappearance of these pigment-cells. Tliey 

 disappear as in individuals living under normal conditions, but after 

 prolonged exposure pigment-cells reappear. The first fact proves that 

 the disappearance of the pigment-cells from the lower side in the 

 metamorphosis is an hereditary character, and not a change produced in 

 each individual by the withdrawal of the lower side from the action 

 of light. On the other hand, the experiments show that the absence of 



