XVII. HEREDITY, VARIATION, PLANT AND ANIMAL 



BREEDING 



Problems. — To determine what inahes the offspring of ani- 

 mals or plants tend to he lihe their parents. 



To determine what makes the offspring of animals and 

 plants differ from tlteir parents. 



To learn about some methods of plant and animiol breeding. 



(a) By selection. 



(b) By hybridizing, 

 io) By other methods. 



To learn about some methods of improving the human race. 



(a) By eugenics. 



(b) By euthenics. 



Suggestions for Laboratory Work 



Laboratory exercise. — On variation and heredity among members of 

 a class in the schooh-oom. 



Laboratory exercise. — On construction of curve of variation in meas- 

 urements from given plants or animals. 



Laboratory demonstration. — Stained egg cells {a.'scaris) to show chro- 

 mosomes. 



Laboratory demonstrations. — To illustrate the part played in plant or 

 animal breeding by 



{a) selection. 



(6) hybridizing. 



(c) budding and grafting. 



Laboratory demonstration. — From charts to illustrate how human 

 characteristics may be inherited. 



To THE Teacheb. — The contents of this chapter will probably prove of more 

 interest and, if seriously taken up by teacher and pupils, of more lasting value than 

 any other part of the course. The immense significance of variation and heredity 

 and the application of these factors in eugenics certainly make a theme of vital 

 interest. The direct teaching of sex hygiene in the public secondary school is not 

 recommended, both because of lack of preparation on the part of teachers, because 

 of the intimacy of contact required between teacher and pupil, making work with 



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