CHAPTER XXIII 



HEREDITY 



General Features of Heredity 



Nature of Heredity. — By heredity we mean chiefly the 

 resemblances between organisms and their ancestors. Despite 

 the numerous differences between successive generations of 

 plants and animals, there remain those resemblances which bind 

 together the successive generations of the different kinds of plants 

 or animals. When we plant a certain variety of Sweet Corn or 

 Flint Corn, we expect to harvest the variety planted and not some 

 other variety. The individuals of each successive crop differ in 

 numerous ways from the individuals of previous crops, but in 

 fundamental features they are alike. That children resemble 

 their parents in habits, disposition, color of eyes and hair, and 

 so on, is so noticeable as to be a matter of common observation. 

 Chiefly upon resemblances, plants and animals have been classi- 

 fied into varieties, species, genera, etc. It has been possible to 

 make such classifications because of resemblances that run 

 throughout generations and remain more or less permanent. 

 One who is endeavoring to improve plants or animals largely 

 attaches his hopes to the fact that offspring resemble their 

 ancestors and especially their parents. 



In addition to resemblances, also many differences are due to 

 inheritance. Although children commonly resemble one parent 

 more than the other, they always have some traits of both 

 parents. In other words, the children show a new combination 

 of characters. Furthermore, no two children are aUke m the 

 combination of parental characters they display. Also children 

 often take after their grandparents or more remote ancestors 

 They may have their grandfather's nose, their father's eyes, and 

 their mother's disposition. It is also obvious that we mhent much 

 that does not express itself. If we have our father's eyes, then 

 what we inherited from our mother in respect to the character 

 of her eyes does not express itself. It remams latent. Each 



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