68 Study of Right- and Left- Handedness 



are rather restricted, so that the ratios cannot be considered exact ; and 

 the discrepancies from the average given by individual rows are well 

 within the limits of probable error. We may conclude with a certain 

 degree of safety that the position of the seed on the ear has no effect 

 upon the method of folding of the first leaf of the seedling. 



Oats. 



The mature plant of many species of the Gramineae exhibits a more 

 or less pronounced tendency on the part of the leaves to twist loosely 

 into the form of a screws The direction of the screw is constant, so far 

 as known, in the case of the common cereals, and it is sometimes used 

 as a diagnostic character for distinguishing different crops in their early 

 stages I 



The leaf-blades of Barley, Wheat and Rye are rolled to the right 

 (i.e. like an ordinary right-handed screw), while Oats show leaf-blades 

 rolled to the left. This twist is quite independent of the mode of 

 folding of the leaves in the young state (and of the leaf-bases when 

 mature); all the leaves of the same plant showing the same twist, 

 although the direction of folding is normally reversed at successive 

 nodes. 



We have seen that in Barley, where the leaves exhibit a right- 

 handed torsion, there is a definite and constant excess of seedlings 

 whose first leaf shows the mode of folding which I have called left- 

 handed. The question thus arises whether Oats, in which the leaf-blades 

 show the reverse or left-handed torsion, will give a different ratio 

 between seedlings showing the LH and RH modes of folding of the 

 first leaf. 



A sowing was made of a random sample of "Thousand Dollar" Oats, 

 and the seedlings were counted for rights and lefts. There were found 

 469 LH and 576 RH. That is to say, there exists in Oats a consider- 

 able excess of right-handed seedlings. The ratio LHjRH is 0*814 

 (44*88 7o LH) ; whereas in Barley (adding together all the varieties 

 studied) it is 1*4016 (58*362 7„ LH) (above, p. 56). 



We thus find that, in the cases of Barley and Oats, the reversed 

 torsion of the mature leaves is accompanied by a reversal of the ratio 

 between left- and right-handed seedlings in respect of the fold of the 

 first leaf What is the nature of this association, or whether it is 

 merely fortuitous, it is impossible at present to decide. 



1 Hackel, " Gramineae," in Engler and Prantl, Nat. Pflfam. n. 2, p. 4. 

 * Percival, Agricultural Botany, p. 511. 



