INTRODUCTION 9 



or animal tends to be like the parent or parents in general 

 characteristics but there are usually evident differences 

 in some respects; no two individuals can be precisely 

 alike. Variation in the offspring may take place in any 

 direction, as in the size or color of the flower, the sweetness 

 or juiciness of the fruit, the prolificacy (16), the vigor (9) 

 or the hardiness (10). It follows that in culture certain 

 individual plants or animals are more desirable to the cul- 

 tivator than others, because the individuals possess dif- 

 ferent qualities. 



19. The principle of selection. — Since the offspring 

 tends to resemble the parent or parents, we may gradually 

 improve plants or animals in the direction of greater useful- 

 ness by selecting the most desirable individuals for repro- 

 duction. For example, by saving and planting seeds 

 from the plants that produce the finest petunia or pansy 

 blossoms, we secure finer flowers than if we gather seeds 

 without regard to parentage. 



20. Breeding in plants and animals is reproduction, 

 watched over and directed by man, with reference to 

 securing special qualities in the offspring. It is based on 

 the principle that the peculiarities of the parent or parents 

 tend to be reproduced, and may be intensified, in the 

 descendants. But before we are prepared for the study 

 of breeding, we need to know something of the principles 

 of classification. 



21. Classification is the arrangement of the different 

 kinds of plants and animals into groups and families based 

 on individual resemblances. If we examine plants as 

 they are growing in nature, we may observe (a) that 

 there are many plants of the same kind, and (6) that there 

 are many kinds of plants. The different plants or animals 

 of the same kind are called individuals, and, in general, 



