554 Introduction to the Study of Science 



richly flavored in contrast with the usual hard cheddar or so- 

 called American cheese. 



Molds of certain kinds modify food materials in several dis- 

 agreeable ways, as in appearance, taste, odor, and in the begin- 

 nings of disintegration, which is a forerunner of decay. It is 

 not difficult to find in any place where foods are kept molds 

 that are responsible for these results. 



Parasites. The fungi or molds that get their food from 

 living organisms, either plant or animal, are parasites. The 

 organism upon which they live is called the host. The fungi 

 may be the active cause of disease, or they may enter the body 

 after a disease has begun, and aggravate it to a dangerous 

 degree. 



The disease-causing molds or fungi that infect man and 

 other animals are usually restricted to limited areas or organs, 

 such as the ear, nose, mouth and throat passages, the lungs, and 

 the skin. A common disease known as ringworm, or in a more 

 severe form sometimes called barber's itch, is caused by a 

 particular species of mold. This mold attacks men and many 

 domestic animals, such as the horse, dog, and cat, which spread 

 the infection. It is restricted to the harder, drier parts of the 

 skin, upon which it may form scabs and from which the hair 

 falls out. The disease, while not serious or affecting the general 

 health, is irritating and difficult to heal. It is easily com- 

 municated through contact or by the use of articles that have 

 been handled by an infected person. A fungus that is indi- 

 rectly of some use to man is called the fly fungus, which in the 

 latter part of summer causes an epidemic among flies. 



Molds that cause diseases of plants and plant products can 

 be mentioned here only in the briefest way. Molds in general 

 initiate the decay of all fruit and vegetables. They also start 

 the wet-rot and dry-rot of potatoes and cause potato scab. 

 The black rot, brown rot, and bitter rot of fruits, the smuts 

 and rusts of grains, such as oats, wheat, and corn, the mildews 

 on grapes and other plants, are all of them due to parasitic 



