140 Natural Theology. 



woody fibre, in starch and sugar, in the nutritious 

 grains and delicious fruits, those very materials 

 which but for them would have generated deadly 

 disease. They then throw back from the leaves 

 the liberated oxygen, partly at least in that active 

 form known as ozone, in which it is most efficient as 

 a purifier of the air. Not only do the plants thus 

 stand ready to save animals from the effect of their 

 own poisoning influence upon the air, but they seem 

 to have committed to them the task of protecting 

 animal life from the poisons produced by general 

 decomposition, both by gathering up the poison and 

 also by some of them showing by their very pre- 

 sence the existence of poisons, and thus warning 

 intelligent man of his danger. 



On the stagnant pool the green film gathers, to 

 many appearing the cause of disease, but in reality 

 the safeguard which nature has prepared ; a thin 

 veil with chemical power which she has spread 

 over such places to gather up and condense a por- 

 tion of the poisons, and to be a token of their pre- 

 sence. Around our southern swamps she has hung 

 the long moss in rich festoons upon the trees, and 

 woven the thick barrier of climbers, through both 

 of which much of the air is strained. 



The plants are thus more than a sign that poi- 

 sons are generated there ; they feed upon and de- 

 stroy them. 



In studying these relationships, it soon becomes 

 apparent that the vegetable kingdom is in general 

 subservient to the animal. The lower is made to 



