The Production of New and Improved Varieties of Timothy 369 



The isolation of the fields from which seed is to be taken must neces- 

 sarily form an important factor in the seed production of timothy varieties. 

 Timothy is naturally cross-pollinated to a considerable extent, the pollen 

 being carried by the wind; nevertheless, observations during the experi- 

 ments have shown that a considerable part of the seed naturally produced 

 is evidently self-fertilized. While no distance of isolation that is practi- 

 cable under ordinary conditions would entirely prevent the possibility of 

 crossing, it is believed that one to two hundred feet, if accofnpanied by 



Fig. 95. — An isolated plat of a pure strain, planted in a rye field to protect it from 



pollination with other types 



some barrier that may be fonned by a surrounding taller crop, such as 

 rye, will give sufficient isolation in seed production for practical purposes. 



probable value of the new races produced 



It may seem surprising to those unfamiliar with plant-breeding prin- 

 ciples that such striking results as are shown in Table 3 can be obtained 

 in so short a time. It is truly rather remarkable, but is in no sense a 

 greater increase than would be expected under the conditions. When it 

 is remembered that timothy is one of the crops most generally grown in 



