12 Principles of Plant Culture. 
7. Culture Deals with Life. All the products of cul- 
ture, whether obtained from the farm, garden, orchard, 
nursery or green-house, proceed directly or indirectly from 
plants or animals, both of which are living beings. A 
knowledge of the conditions that sustain and promote life, 
is, therefore, the foundation to a broad knowledge of hus- 
bandry. 
8. What is Life? We know nothing of life except as 
it is manifested through the bodies of plants and animals. 
Within these, we can define, within certain limits, the range 
of environment in which it can exist; we can hinder or 
favor it; we can destroy, but we cannot restore it. We 
know that it proceeds from a parental body similar to its 
own, that the body it inhabits undergoes a definite, progress- 
ive period of development, at the end of which the life dis- 
appears and the body loses more or less promptly its form 
and properties. 
9. Vigor and Feebleness are terms used to express 
the relative energy manifested by the life of different living 
beings. Certain trees in the nursery row usually outstrip 
others in growth, i. e., are more vigorous than others. One 
pig in a litter very often grows slower than any of the 
others, i. e., is more feeble or less vigorous than any of the 
others. Feebleness is the opposite of vigor. The most 
vigorous plant or animal usually attains the largest size, and 
as a rule, is most satisfactory to its owner. Vigor is pro- 
moted by a favorable environment. It is usually greatest 
in rather young plants and animals, and declines with ad- 
vancing age. It may be reduced by disease or improper 
treatment, and when thus reduced is often difficult to re- 
store. Reduced vigor often tends to early maturity and 
shortened life, and sometimes to increased prolificacy. 
