160 MAIZE 



CHAP. Argentina, France, Italy, the Balkans, India, Australia, Egypt, 

 Somaliland, Nyassaland, and all the breeds and strains com- 

 mercially grown in different parts of South Africa, the writer 

 has reached the conclusion that none of them gives the best 

 results which it is possible to obtain under South African con- 

 ditions, and that it is necessary to breed improved types which 

 will meet the varying conditions of different parts of the 

 country, and combine high yield with market requirements. 

 A good market has been established for South African maize, 

 and the country must see to it that it is kept supplied with a 

 steadily increasing quantity of grain suited to its various 

 demands. 



Inheritance of Characters. 



119. Fluctuations. — There are some plant-characters, such 

 as relative height of stem, number of leaves, size of leaf, length 

 of ear, etc., which are not stable, but are more or less in- 

 fluenced by conditions of environment such as richness or 

 poverty of soil, sufficiency or lack of moisture, temperature, 

 and sunshine. These have been termed fluctuations, and "we 

 have no valid reason for supposing that they are ever inherited " 

 {Punnett, I, p. 133). Such variations have also been called 

 "acquired characters". They are not to be confused with 

 mere mutilations, due to borer, hail, smut, etc., which are not 

 known to be transmitted. 



120. Heritable Characters. — There are other characters, 

 such as colour and shape, flintness or dentness of grain, which 

 are not dependent for their manifestation on the influence of 

 environment. These are transmitted from parent to offspring. 

 When such a character affects the vegetative part of a plant, 

 as for example the height of the stem, number or breadth of 

 leaves, etc., it may be difficult to tell whether it is a fluctuation 

 or a heritable character, except by growing it on for one or 

 two generations. 



121. Importance of a Knowledge of the Laws Governing the 

 Transmission of Characters. — Improvement by scientific breed- 

 ing must depend on a knowledge of the laws and methods of 

 the transmission of characters from parent to offspring, inas- 

 much as such knowledge will (1) prevent the selection of 

 parents unfitted to produce definite desired results ; and (2) 



