206 The Farmstead 



Owing to the short time which has been de- 

 voted to the study of bacteria and their func- 

 tions, closer attention has been paid to the 

 harmful or pathogenic bacteria because of their 

 relation to human health. This one-sided study 

 of bacteriology has blinded us to the beneficent 

 action of many bacteria, and has caused us much 

 unnecessary fear of their presence in food. 



The harmful bacteria cause disease either in- 

 directly through poisons which they excrete in 

 food products, or directly by poisons or toxins 

 which they form when living within the body. 

 Although harmless bacteria are everywhere pres- 

 ent, the pathogenic or harmful varieties are 

 ordinarily much less numerous. It should be 

 understood, however, that many of the so-called 

 harmless bacteria are the cause of certain de- 

 compositions of vegetable and animal matter 

 with the formation of substances which are 

 detrimental to health. This is illustrated by the 

 occasional cases of meat, fish, and oyster poi- 

 soning. The pathogenic bacteria, such as those 

 of tuberculosis, typhoid fever, diphtheria, and 

 the like, constitute, as has been already stated, 

 a small number of species. These are dissemi- 

 nated through various channels, such as the milk 

 and the water supply, and by persons directly. 

 When they are introduced into dirty and un- 

 wholesome homes, they find in the filth suitable 



