Appendix E 437 



prising as great a variety of unit characters as possible. A small 

 bundle of stems for each student containing samples from different 

 plants. Photographs and mounted specimens. Varieties of 

 oats comprising various unit characters that may be readily 

 distinguished in hybrid plants, such as black and white grains, 

 side and panicled types of inflorescence; also bearded and 

 beardless varieties of wheat or barley. Specimen plants of 

 parent types should be available for inspection, also specimens 

 of the FI plants. A large number of F 2 plants resulting from each 

 cross studied should be available for examination by the class. 



Program. 1. The instructor should first explain the purpose 

 of the afternoon's exercise and outline the order of procedure. 

 Unit characters are to be studied and illustrated with timothy 

 and oats or barley. Dominance, recessiveness (or presence and 

 absence), segregation, and recombination can be illustrated here. 



2. At this occasion a talk may well be given on artificial 

 crossing of small cereals for the purpose of creating new varieties. 

 The instructor may describe the inflorescence of the oat plant, 

 and the technique of making crosses in these plants. He should 

 illustrate the talk with charts and with diagrams made on the 

 blackboard. 



3. Mounted specimens of oat types together with the FI and 

 F 2 progeny resulting from their crossing may be handed around 

 for examination by the class. If enough mounts are available, 

 the specimens may be drawn and described by each student. 



4. Composite samples of timothy should be handed to each 

 student. He should study them to see what diversity of unit 

 characters can be found there, in the nature of differentiating 

 botanical characters. A list should be made of all the unit 

 characters observed. Drawings of timothy heads may help to 

 train his observation and fix the idea. 



5. A large progeny of F z oat plants should be distributed 

 among the class after the parent types have been shown and their 

 differentiating characters discussed. The class may now examine 



