EXPERIMENTAL STUDY OF HEREDITY 73 



in part. There seems to be evidence both ways, but the 

 bulk of the evidence and the weight of scientific opinion 

 is against the inheritance of acquired characters as here 

 defined. We can arrive at the correct answer only by care- 

 ful experimentation, that is, by asking questions of nature. 1 



2. Can the inheritance of a strain be artificially altered? 

 This is a question of the very first importance. If the 

 inheritance could be so altered the marvels that breeders 

 might perform would be greatly increased. A blue rose 

 (the despair of all plant breeders) might possibly be pro- 

 duced by sufficiently careful and extended experiment- 

 ing; disease and undesirable traits of character might be 

 eliminated from certain tainted family strains by artificial 

 treatment. On the other hand, by an unfortunate com- 

 bination of circumstances, most undesirable and re- 

 grettable results (e.g., a weed poisonous to cattle, or a new 

 and virulent disease-causing bacterium) might be experi- 

 mentally produced. The experiment has been made of 

 exposing the ovaries of flowers to the rays of radium, and 

 of injecting them with various chemical substances, with 

 an idea of altering the physical or chemical nature of the 

 egg-cells, and thus altering the inheritance. The results 

 of such experiments, so far tried, need to be further con- 

 firmed before we can say with certainty that the result 

 sought has been accomplished. 



3. How may dominance be explained? Why is tallness 

 dominant over dwarfness, brown eye-color over blue, 

 any one character over any other? At present we can 

 only speculate on these questions. 



4. What is the mechanism of inheritance? In other 

 words, by what arrangement and interaction of atoms 



L On the inheritance of acquired characters, see Thomson, J. A., 

 Heredity. London, 1908. Chapter VII. 



