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one. So in the substantial fabric of the world part is bound to part. In 

 wind and weather, or in the business of our life, we are daily made aware of 

 results whose first conditions are very remote; and chains of influence, 

 not difficult to demonstrate, link man to beast and flower to insect. The 

 more we know of our surroundings the more we realize that Nature is a 

 vast system of linkages, that isolation is impossible." 



The Balance of Nature. 



Nature has evolved not as independent but often as closely dependent 

 organisms. The well-being of one set is frequently related in many ways 

 to other sets, and no creature can be said to live unto itself. Insects and 

 plants, for example, have been for long ages mutually adapting themselves 

 one to the other, the plant to the insect and the insect to the plant. We 

 all know how birds keep down insects and many rodents; in fact, an ap- 

 proximate equilibrium, has been established between them. Any disturb- 

 ance or sudden reduction in the numbers of the birds of a region is sure 

 to disturb the equilibrium or balance in the insect world and cause much 

 loss to the crops upon which the insects feed. 



Moreover, the number of carnivorous animals bears a definite propor- 

 tion to the herbivorous animals upon which they feed, the herbivorous 

 animals to the plants, the plants to insect visitors, etc.. In this web of 

 Nature we may note that the animals preyed upon are more prolific than 

 the predaceous forms. "Small rodents tend to be much more prolific 

 than carnivores. The primary reason for this is probably that less in- 

 dividuated types tend to be more prolific." — (Thomson). 



Drs. Russell and Hutchison of the Rothamsted Station have shown 

 that fertility of the soil depends upon the number of certain protozoa in 

 the soil. These feed upon the bacteria which work up available plant food 

 and if they are reduced in numbers the bacteria multiply and perform their 

 their beneficent mission. 



Sometimes man interferes with the balance of Nature and serious con- 

 sequences follow. Rats became a great plague in Jamaica and to offset 

 them the mongoose, a weasel-like animal, was introduced. The mongoose 

 made short work of the rats, but it turned its attention to useful animals 

 such as poultry, ground-birds and insect-eating lizards and snakes. As a 

 result injurious insects and ticks have increased greatly, and both plants 

 and animals have suffered much injury. 



The English sparrow was introduced into America about 1860, and 

 soon increased and spread rapidly. It is blamed not only for driving 



