Page:The Effect of Research in Genetics on the Art of Breeding (1912).djvu/14

12 *Leaves
 * Long or short.
 * Broad or narrow.
 * Erect or reversed.
 * Rolled or flat.
 * Clustered at base or extending to top of culm.
 * Culms
 * Tall or short.
 * Thick or thin.
 * Straight or wavy.
 * Erect or bent outward.
 * Green or purplish.
 * Many or few.
 * Nodes
 * Many or few.
 * Green or brown.
 * Internodes long or short.
 * Habit Characters
 * Lodging or non-lodging.
 * Rusty or rust resistant.
 * Early or late season.

It is possible that some of these characters may be expressions of the same unit, but in a number of cases they certainly represent several different unit characters. For instance in length of head, height of culm, number of culms, and season of maturing, several different degrees are certainly present which are fully heritable. Doubtless there are many more than 28 pairs of unit characters which could be distinguished by careful study. If we have two pairs of characters, such as tall or short and early or late, we know that 4 homozygous combinations are possible. If three pairs are considered, 8 combinations are possible. Every time we add a different character pair we double the number of different combinations that are possible. Twenty-eight character pairs would thus give us as many possible combinations as 2 raised to the 28th power, or the astonishing number of 268,435,456. It would be possible then to produce this tremendous number of different varieties of timothy if there was any reason to do so, and each variety would be distinguished from any other variety by one distinct character and would reproduce true to seed.

The task of the breeder, then, is to find which among these character combinations gives the superior plant for commercial cultivation. He will soon eliminate certain characters as unimportant and concentrate his attention on those qualities that are essential.

It would be interesting to discuss the factor hypothesis, purity of germ cell, sex-limited inheritance and other important problems connected with inheritance studies, but I have already too severely tested your endurance.

As breeders and genetists we have every reason to congratulate ourselves on the rapid advance of our science and the growing recognition of the importance of the subject in practical agriculture. Colleges throughout the country are extending their courses of study to include genetics. In almost all of the experiment stations studies on genetics and practical breeding are now given fully as much attention as any other subject. With all of this advance, however, only in a few institutions have there been established special professorships or investigatorships in breeding or genetics. If the subject of genetics is to be properly taught or the investigations are to reach the highest standard, it is clear that men should have this as their special and recognized field. The subject should no longer be assigned indiscriminately to the horticulturist, agronomist, animal husbandmen or dairymen. We must establish more professorships of genetics or breeding.