24 THE STORY OF THE BACTERIA. 



posed. Both are alike worked over by the 

 digestive organs, under ordinary conditions, 

 into nutritive material for the uses of the 

 body. 



There are poisonous vegetables, and there 

 are, more 's the pity, as we shall see by and 

 by, poisonous bacteria, but we do not shudder 

 as we swallow a mushroom to think what 

 might have happened to us if we had swal- 

 lowed a poisonous toadstool instead ; we sim- 

 ply trust to the gardener, or if he is dishonest 

 or ignorant, see to it ourselves that the poison- 

 ous are not liable to get in with the other 

 plants, and then go on enjoying our delicacies 

 like sensible people. 



It will thus be seen that the role of the 

 bacteria in nature, though humble and silent, 

 is an exceedingly important one. They are 

 indispensable to the continuance of the higher 

 forms of life upon the earth. They may well 

 be called man's invisible friends. 



