DISTRIBUTION OF M1CROORGANSMS 65 



ence to temperature, moisture, food, and removal of by- 

 products. The feces of all animals are especially high in 

 Iwleria. The bacteria are present in the superficial layers 

 of the skin. 



The tissues of plants are undoubtedly free from bacteria. 

 They are present on the surface of the leaves in such num- 

 bers and vary so much from the normal soil flora that 

 it is certain growth occurs thereon. The occurrence of 

 bacteria on plants has been studied but little. 



