266 Transactions of the Boyal Society of South Africa. 
have noticed Id-row ears in this breed, all the parent ears for two or three 
generations having been 8-, 10-, or 12-rowed. 
At the same time there is ample indication that within certain limits 
row-numbers are inherited in the maize plant, but it is doubtful whether 
any strains grown in South Africa are sufficiently pure bred for this 
character, to demonstrate the point with absolute certainty. 
III. 
INHERITANCE OF ROW-NUMBERS IN CROSS-BRED MAIZE. 
The following is an advance note on the result of crossing an 8-rowed 
white dent maize 2 (No. 904) with an 18-row yellow dent ^ (No. 905) 
and of the reciprocal cross. Difficulty having been experienced in obtain- 
ing in South Africa any breeds of maize pure as regards row-numbers, I 
approached the United States Department of Agriculture, and with its 
kind assistance was enabled to obtain in 1909 what I required ; both 
types bred true, and the cross and reciprocal cross were made in the 
season 1909-10. 
White dent S-roiv 2 X Yelloiv dent IQ-roio ^ . — The ears produced as 
the direct result of cross-pollination bore all the visible characters of the 
mother plant, differing only in the cross-bred grain being yellow with a 
white cap. 
Yelloiv dent IQ-roiu $ x White dent 8-rotu $ . — The ears produced as 
the direct result of cross-pollination bore the visible characters of the 
mother plant, differing only in the cross-bred grain having a white or 
light-yellow cap. 
The F.l generation. — The heterozygous grains obtained in 1909-10 
were planted in the early part of the season 1910-11. Fifty-two plants 
were grown ; these were carefully hand-pollinated with pollen from plants 
bearing the same record-number, i.e., of the same parentage. The 
technique employed was to cover the ears with a loose paper bag. tied at 
the neck, as soon as the silks " appeared. Pollen was collected by 
pulling the tassel, keeping the same overnight in a jug of water in a room 
free from draught, and during the succeeding three days collecting in a 
seed-envelope the pollen which fell on to a newspaper placed beneath for 
the purpose. To apply the pollen the bag was removed and sufficient 
pollen shaken on to the silks ; the process was repeated twice, at intervals 
of seven to ten days, fresh pollen being collected for each operation. 
This usually resulted in the production of well-developed ears. 
Thirteen plants were destroyed by stalk-borer, wind-storm or accident ; 
leaving thirty-nine ears to be dealt with. 
Explanation of Becord-mimhers. — The following record-numbers are 
used in the tables : — 
