22 Structural Characters : Plants \q\\. 



7. Rough and smooth foliage. Wheat. Biffen (27). 



8. Keeled glumes and rounded glumes. Wheat. Ibid. 



9. Beardless and bearded ears. Wheat. Ibid. Also 

 Spillman (247) and Tschermak {270). 



Most, if not all, of the "beardless" varieties exhibit a slight and variable 

 amount of awn especially on the uppermost spikelets (Fig. 6). 



10. The "hoods" or '' Kapuzen' characteristic of 

 certain Barleys show a partial dominance over the normal 

 type. These hoods. Professor Biffen states, are, structurally, 

 aborted florets (Fig. 5). Tschermak (270), Biffen (30). 



11. Hollow and solid straw. Wheat. Biffen (27). 



This is a structural character of an interesting kind, and one upon 

 which the commercial value of straw very largely depends. It was shown 

 that many factors were concerned in the production of the stem-characters; 

 and in F^ by the recombination of these factors a great variety of straws 

 appeared. 



12. Blunt and pointed pods. Pisum. Tschermak 

 (271), R.E.C. (20). Phaseolus. Tschermak (272). 



The dominance in this case is complete. Some varieties exist in both 

 a blunt and a pointed type {e.g. Sutton's Continuity). The nature of these 

 cases is discussed later. 



13. Lax and dense ears of Wheat and Barley give 

 different results according to the varieties used. Sometimes 

 F^ is lax, sometimes it is intermediate (Spillman, 247; 

 Biffen, 27, 28). See Fig. 6. In Barley an increase in ear- 

 length has been observed (Fig. 5). 



14. Development of fibrous parchment-like lining to 

 pods, and the absence of the same which constitutes the 

 *' sugar peas." Pisttm. In Phaseolus (kidney-beans), where 

 similar types occur, the evidence is that the dominance is 

 reversed (Emerson, 120, 121). 



This is one of the features originally investigated by 

 Mendel. He regarded the parchmented type as a dominant. 

 In our experiments F^ has always had some parchment but 

 the quantity is so much reduced as to cause the heterozygote 

 to have a very distinct appearance (R.E.C. 20). 



15. Much serrated and little serrated edges of leaves. 

 Urtica (cp. Phyteuma, Correns, 70, p. 197). This cross 



