262 APPLIED BIOLOGY 



animals. The danger from poisonous mushrooms is well 

 known. Certain molds may grow in the lungs of birds, 

 other animals, and very rarely in man. The smut of rye 

 and other plants produces a poisonous substance known as 

 ergot, which sometimes poisons farm animals. In very 

 small quantities ergot is used in medicine. There is always 

 danger in the use of moldy foods by men or farm animals, 

 for molds often form poisonous substances under conditions 

 not yet understood in science. There is good reason for 

 thinking that a large number of small chicks are killed each 

 year by moldy food ; and several scientists believe that the 

 mysterious disease pellagra, which has recently attracted 

 so much attention in the southern states, is caused by some 

 form of mold growing in corn meal, which is extensively 

 used as food. Certainly it is best not to use corn meal or 

 other cereal foods if there is about them the least evidence 

 of mold or a musty odor, which indicates some kind of 

 molding. 



Other diseased conditions due to molds are thrush, a 

 disease of the mouth-cavity of infants; ringworm, often 

 seen on human faces and scalps; and other skin diseases 

 caused by mold-like plants whose mycelia grow in the human 

 tissues. Most of these are easily prevented. The spores 

 of all the mold-like plants which cause skin diseases may be 

 distributed by towels, sponges, combs, and barbers' tools. 

 Such articles should be carefully washed in boiling water 

 and strong soap after being used by diseased persons. The 

 laws in many states now require such precautions in barber- 

 shops. 



Useful Molds. So many of the molds and their allies 

 are injurious from our human point of view that we must 

 guard against the erroneous impression that all relatives 

 of the molds are harmful. The following examples will 

 suggest some useful aspects of the life of these lower fungi. 



The common molds which cause decay oftentimes destroy 



