70 



PHYSIOLOGICAL PROCESSES IN PLANTS 



Conclusions. 1. If pollen is transferred from one flower to anothei 

 flower of another variety, it is termed cross-fertilization. Why ? 



2. Why cut away the anthers from one of the flowers ? Why inclose 

 the other in a paper bag until it is ripe ? 



Observations. 1. After the pod or fruit of the pollinated flower starts 

 to grow, remove the bag. Permit the fruit to ripen. Does it differ from 

 either of the fruits of the parent plants ? 



2. Try ripening the fruits and planting the seeds, in order to deter- 

 mine the effect of the 

 cross-pollination. 



Note. Methods simi- 

 lar to the above are in use 

 by Burbank and others 

 in producing new varie- 

 ties of fruits. Such pro- 

 cesses are part of the 

 work of plant breeding. 



e. Comparison with 

 Animals 



Observations. 1. 



Study Figure 15. Which 

 of the dogs is specialized 

 for speed? Driving 

 cattle ? 



2. Which is especially 

 prized for stopping cattle ? 

 Trailing by scent? Find- 

 ing game? Drawing ve- 

 hicles ? Going into holes ? 

 Cold weather? House 

 pet? 



3. A hairless dog is 

 much prized in hot cli- 

 mates, as in Mexico, etc. 

 Why? 



Conclusions. 1. It is 

 claimed that widely dif- 

 fering environments 

 under various forms of domestication cause sports. What do you 

 think is meant by such a term ? Are they accidental or designed by 

 man? 



FIG. 15. Artificial selection among dogs. 

 (After Romanes.) 



