26 Structural Characters: Plants [CH. 



23. Flat standard and hooded standard in the flower of 

 Sweet Pea. R.E.C. (22). See Plate V. Some very curious 

 phenomena have been observed in this case, which are 

 described in Chap. ix. The type known as "Snapdragon," 

 perhaps an extreme form of hood, is also a recessive to the 

 flat type. R.E.C. (20, p. 83). 



24. Imbricated petals and stellate or "star "-type. 

 Primula Sinensis. Observations made at Messrs Sutton's 

 and experiments of R. P. Gregory with W. Bateson. (See 

 Fig. 14.) 



25. The monstrous condition of the calyx in which it 

 resembles the corolla, seen in " hose-in-hose " Campanula is 

 an imperfect dominant to the normal. Associated with this 

 homoeotic variation, the female organs are more or less 

 completely sterile in certain strains. Correns (76). This 

 subject is discussed in Chap. xi. 



26. Abortion of the female organs in the lateral florets 

 of Barley, as found in the 2 -rowed types, and the complete 

 or hermaphrodite development of the florets, as in the 

 6-rowed types (Fig. 8). Tschermak (270) and (275), p. 1 1. 

 Biffen (30). 



This case is somewhat complex. There are three types, (i) Six-row, 

 in which 3 perfect hermaphrodite florets are developed in each spikelet. 

 All set seed and the result is that the ear has 6 rows of seeds. (2) Types 

 in which the lateral florets have anthers but no female organs. (3) The 

 " Abyssinian " type in which the lateral florets contain neither male nor 

 female organs. The types (2) and (3), being able to make seeds only in 

 the central florets of each spikelet, alike develop two rows of seeds. 

 When (i) is crossed with (3), F v is like (2); and (2) crossed with (3) gives 

 FI also like (2). Some further complexities have been observed, but in 

 general it appears that the dominant factor has the power of partially 

 preventing the formation of the reproductive organs in the lateral florets. 

 The facts may perhaps be interpreted as bearing on the phenomenon of 

 Sex. 



Tschermak (275) describes crosses between a 2-row and a "4-row" 

 type. From Professor Biffen I understand that the latter is in reality a 

 lax-eared 6-row type. F^ is 2-row, and in F z the ratio is 12 2-row : 

 3 "4-row" : I 6-row. This is a special case of the ratio 9:3:3:1, lax- 

 ear and 2-row being dominants. Tschermak and Shull (242) regard it as 

 an illustration of the effects of a latent factor. 



