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CHAPTER XII 



GENETICS AND EUGENICS 



(By Frank G. Brooks, Cornell College, Iowa) 



The History of a Great Discovery 



Like father like son" is a very ancient adage. Since man has 

 been able to think, he has pondered the problem of heredity. Al- 

 though very early he had observed evidence of the inheriting of 

 parental characters by the offspring of the various forms of life with 

 which he was familiar and was convinced by these observations that 

 heredity did take place, he has not known the ''how" or ''why" of it 

 until recently. The science of heredity, therefore, is very new. The 

 fundamental law on which it is based was announced by Gregor 

 Johann Mendel in 1866. However, Mendel, an Austrian monk, pub- 

 lished his discovery in an obscure journal and it did not receive 

 general recognition until its rediscovery in 1900. 



Mendel's success in finding the underlying principle of heredity 

 was due, in part, to his choice of an experimental unit. Instead of 

 following the usual trend by considering how a parent conveys his 

 various traits to his offspring, thus making the individual the unit of 

 observation, he chose a definite inheritable character and considered 

 how it was transferred from many parents to all their offspring. In 

 addition to this wise choice of an investigational unit the patience, 

 mathematical ability, skill as a gardener, and analytical insight of the 

 investigator contributed also to the success of the research. 



Mendel chose the garden pea as the material for his work. This 

 was a fortunate choice for, although the law that he was to discover 

 underlies practically all inheritance, it is not always as free from 

 complications as it is in the case of those traits of the pea which he 

 investigated. 



Mendel's Law 



For one of his projects he planted seeds from stock that had been 

 known to produce nothing but tall plants for many generations. He 

 planted also seeds from stock that had produced nothing but dwarf 

 plants. When the two types of plants were in blossom, he transferred 

 the pollen from the stamens of the one to the stigmas of the other. 

 The seeds that resulted from the cross were collected and planted. 



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