136 HEREDITARY CHARACTERS 



quite another kind for the transmission of parental acquire- 

 ments. 



In considering the evidence available with regard to the 

 effect of the environment upon the characters of the indi- 

 vidual, we find at once that very marked changes are often 

 produced. Nageli took some Alpine plants and placed them 

 in rich soil, under the usual conditions of cultivation, in the 

 Botanical Gardens at Munich. 1 The plants thus removed 

 from their normal environment changed in their characters 

 so enormously that they would not have been recognised. 

 The seeds of these plants grown in the Botanical Gardens 

 reproduced the acquired characters of their parents, and this 

 went on for about thirteen years. When, however, the plants 

 were removed to poor and stony soil, the acquired characters 

 disappeared, and the seeds of the plants in the Botanic Garden 

 grown in a poor and stony soil exhibited none of the acquired 

 characters of the parents but only those of the original Alpine 

 ancestors. There was no question of the acquired characters 

 disappearing gradually in succeeding generations under the 

 normal conditions of Alpine plants ; only the inborn characters 

 appeared, and the characters produced by the environment 

 left no trace whatever even for one generation. Here we 

 obviously have a very good illustration of the effect of the 

 environment upon the characters of the individual, but no 

 evidence whatever that the modifications acquired by a 

 change in the parental environment produce any effect upon 

 the germ cells. If the offspring were grown in the environ- 

 ment that had produced the acquired characters in the 

 parents, the same result was produced, that is, the offspring 

 acquired similar characters to those acquired by the parents 

 under similar stimuli. All that was proved was that the 

 offspring inherited the inborn capacity possessed by their 

 parents for making certain acquirements. 



Some diseases are often spoken of as being inherited. 

 The only evidence available on this point shows very 



1 Nageli, C. von, Mechanisch-physiologischc Theorie der Abstammungslchre 

 Munich and Leipzig, 1884. 



