Richardson: Wheat Breeding 



125 



most cases these varieties originated 

 from a single plant growing in the ordi- 

 nary field erop. The outstanding quali- 

 ties of these plants arrested the attention 

 of the originator, who harvested them 

 separately, and multiplied the seed for 

 distribution. 



OBTAINING IMPROVED VARIETIES. 



There are two general methods by 

 which improved and new varieties may 

 be obtained, namely, by — 



1. Selection. 



2. Cross-breeding. 



We will consider each of these in some 

 detail. 



Vilmorin, a renowned authority on 

 plant breeding, states that "selection is 

 the surest and most powerful instrument 

 man possesses for the modification of 

 living organisms. ' ' Reduced to simplest 

 terms, it consists merely in the choice of 

 the best individuals for the propagation 

 of seed, and it is by means of selection 

 exercised through centuries that our 

 cultivated plants have reached their 

 present standard of excellence. The 

 obvious effects of selection may perhaps 

 be seen to best advantage in the animal 

 world. It was by patient, systematic 

 selection, exercised over a long period of 

 years, that the famous Booth and Bates 

 types of Shorthorn cattle were devel- 

 oped. What we term pedigreed stock 

 in Merinos, Clydesdales, Jerseys, etc., 

 have been produced by a slow, pains- 

 taking process of selecting the very best 

 animals in the herd, accompanied by a 

 vigorous exclusion of the culls. While 

 the vast majority of farmers are well 

 aware of the beneficent effects of selec- 

 tion in the animal world, they appear to 

 be totally oblivious of the fact that 

 selection can be equally effective when 

 applied to the plant world. 



The term "selection," as commonly 

 used, covers a general, as well as a 

 specific, idea. In its general sense, 

 selection is practiced by every good 

 farmer when he chooses varieties of 

 wheat that are best suited to his soil and 

 climatic conditions, reserves the best 

 portion of his crop for seed purposes, and 

 takes good care to grade his seed well. 

 No well-informed stock breeder would 

 think of selecting as his parent stock 



HOW A LEAF BREATHES 



Above, epidermis of Federation wheat 

 (under surface of leaf) , showing the 

 stomata or breathing pores. "Each 

 stoma or pore consists of two sau- 

 sage-shaped guard cells joined 

 together at the extremities in such 

 a manner as to leave a very narrow 

 sHt-hke pore between them." The 

 stomata open and close in accord- 

 ance with the respiratory needs of 

 the leaf, this movement being 

 brought about by changes in the 

 curvature of the guard-cells, which 

 in turn depend on the turgidity or 

 water content of the ells. Below, 

 the same further enlarged (to about 

 300 diameters). (Fig. 12). 



