INTRODUCTION. 41 



What influence has sunlight on bacteria? 



It is very destructive to bacteria and especially if the rays 

 of the sun come in direct contact with the bacteria. 



What effect has oxygen on bacteria? 



Some bacteria require oxygen for growth and multiplication 

 and are called aerobic; others do not require oxygen and are called 

 anaerobic. 



What are the functions or products of bacteria ? 



The products, functions, or manifestations of bacteria are the 

 production of ptomains, toxalbumens, fermentation, pigments, 

 odors, putrefaction, oxidation, nitrification, and also of diseases 

 in man and animals. 



What are ptomains? 



These are crystallizable basic substances, very much like the 

 vegetable alkaloids obtained from putrefying objects. 



What are toxins and toxalbumens? 



They are complex noncrystallizable substances, somewhat 

 similar to albumen and protein, produced in the animal organism, 

 are very poisonous and considered to be the prime cause of disease. 



What are saprophytic bacteria ? 



Those bacteria that grow outside of the animal body in dead 

 decaying matter. 



What are parasitic bacteria? 



Those bacteria that grow within the living animal body. 



What conditions are necessary to constitute infection ? 



(1) The organism must be able, under proper conditions, to 

 produce disease, whether it be nonpathogenic .or pathogenic; 

 (2) it must be parasitic, that is, have the power of growing within 

 the animal body; (3) the toxins or poisons must be in sufficient 

 quantity; (4) the animal body must be susceptible, that is, the 

 tissues of the body must be in the proper condition for the growth 

 and multiplication of the organisms in sufficient numbers. 



What conditions are usually necessary for an infectious 

 agent to produce disease? 



1. The organism must be found in the tissues of the animal 

 having the disease., 



2. It must be isolated. 



3. It must be grown for generations in culture media. 



