268 Transactions of the Royal Society of South Africa, 
Boio-numbers as Fluctuating Variations. — The range of variation in the 
progeny, from 8 to 16 rows, is prohably due in part to fluctuating varia- 
tion such as is always met with in the maize plant, as for instance in the 
case of a 20-row ear produced by a pure-bred 18-row plant, and as in the 
case of plants which produce both 8-row and 10-row ears on the same 
plant. That this variation is partially dependent on conditions of growth 
is indicated by the frequent occurrence of ears bearing a pair of rows more 
in the lower half than in the upper ; this seems to be especially prevalent 
in seasons which cause a check in growth. This season, which was dry 
during the early summer and wet towards the end, ears have been found 
with a pair of rows more in the upper part of the ear than in the lower. 
But the fluctuating variation in row-numbers appears to be limited, e.g., 
an 8-row type shows fluctuating variation down to 4-rows on one side and 
up to 12-rows on the other side ; I have met with a few cases of 14-row 
ears in a normally 8-row breed, but am inclined to think this may have 
been due to crossing. On the other hand, an 18-row breed may vary to 
24-rows on one side and down to 14 on the other, but I doubt whether it 
ranges below 12. 
Conclusions. — The cross between an 8-row and an 18-row breed results 
in the production of an intermediate form in the F.l generation. Of the 
39 cross-bred ears under consideration only two produced the same 
number of rows as either parent, while nearly 75 per cent, produced 
either 12 or 14 rows ; as regards these two row-numbers, the cross and 
the reciprocal cross produced nearly the same proportions, the 
18-row X 8-row giving 71*5 per cent., and the 8-row x 12-row 
76 per cent. 
It is intended to continue this investigation next year, and to record 
the splitting out in a large number of individuals, especially of the 10-, 
12-, and 14-row ears. 
IV. 
NOTE ON INHERITANCE OF COB-COLOUK IN MAIZE. 
A cross and reciprocal cross made between a white-cobbed, white- 
grained breed of maize (Hickory King) and a red-cobbed, yellow-grained 
breed has resulted in the production in the first filial generation of all red- 
cob ears. This experiment will be continued next year to determine the 
percentages of red and of white cobs which will reappear. This is of some 
importance to the maize-breeder, for red cobs are becoming too prevalent 
in white-grained breeds, to the detriment of the grain. 
