64 Study of Right- and Left- Handedness 



the eight even rows gave an excess of LH seedlings. There are alto- 

 gether three exceptional rows in which the proportion of rights and 

 lefts are reversed, and one in which LH/RH = 1. Such exceptions 

 occur in all the cobs studied, both in even and in odd rows : they are 

 probably to be attributed to fluctuating variability of the same kind as 

 was found in the ratios for ears of two-rowed Barley, and represented 

 by normal curves \ 



It must be noticed that exceptions to the general rule are not 

 lacking in individual cobs, as will be seen on reference to Table V. 

 Cob VII shows a ratio of very near equality for both odd and even 

 rows. Cob XIV shows a ratio of about 1'2, not only for the even rows 

 (where it is normal), but for the odd rows as well : a result which may 

 be compared with that obtained in Barley. Cob XI is the most striking 

 exception, for here the odd rows gave a definite excess of lefts and the 

 even rows a similar excess of rights : this being the exact reverse of the 

 usual results. Another cob, doubtfully of the same variety as cob XI — 

 viz. cob XV — also gave somewhat abnormal results, so that it is 

 possible that different varieties of Maize may behave in different ways^. 

 No further cobs of the same varieties as VII and XIV could be 

 procured. 



But despite exceptions, both in the offspring of individual rows and 

 of single cobs, the general conclusion appears to be justified that odd 

 rows on the Maize cob give an excess of right-handed, and even rows 

 an excess of left-handed, offspring. It remains to find a reason for this 

 behaviour. 



It was thought possible that the position of the ovule with respect 

 to its neighbours, and the consequent differences in pressure which 

 would be experienced by ovules according as they were produced in 

 odd or even rows, might cause differences in the shape of the early 

 environment of the embryo which would be to some extent reflected in 

 the mode of folding of its first leaf. This hypothesis was tested by the 

 following experiment. A cob (XVII) was chosen whose rows were 

 considerably distorted, and whose seeds consequently showed much 

 variety of shape. The seeds were divided into three lots according to 

 the relative thickness of the two lateral edges : looking at the outer 

 end of the seed with the embryo uppermost it was placed in class (a) 

 if the LH edge was narrower than the RH, class (c) if the reverse was 

 the case, or class (b) if it could not be definitely included among (a) 



1 Compton, 1910, p. 501. 



2 Further experiments are being made with this variety of Maize. 



