40 PRACTICE OP EQUINE MEDICINE. 



hesitate to say that each of the infectious diseases is caused by a 

 definite micro-organism or the poisons produced by them. 



No doubt most all diseases are produced directly or indirectly 

 by micro-organisms, ptomains, or toxins, as we know that micro- 

 organisms exist most everywhere, merely waiting for the proper 

 conditions for their growth and multiplication. 



What are bacteria? 



They are microscopic vegetable organisms of the simplest 

 form found in air, water, soil, and decaying organic matter. They 

 are fission fungi or schizomycetes, unicellular, almost always 

 devoid of cholorphyll, generally unbranched, and reproduce them- 

 selves by direct division or fission, spores, or gonidia. 



Name the main divisions of bacteria regarding form. 



1. The globular or spherical-shaped, called cocci; 2. straight 

 rod-shaped forms called bacilli; 3. curved or corkscrew forms 

 called spirilla. 

 How are the cocci divided? 



Into micrococci when small in size; staphylococci or irregular 

 masses ; streptococci or chains ; diplococci or pairs, tetrads, or fours, 

 and sarcinse or groups of eights. 



How are bacteria divided with reference to disease? 



In nonpathogenic and pathogenic. 



What are nonpathogenic bacteria? 



Those bacteria that do not cause disease, as the tissues are 

 not in proper condition for their growth and multiplication. 



What are pathogenic bacteria? 



So called when the tissues are in such condition to allow 

 them to develop and multiply in sufficient numbers to injure the 

 tissues, causing disease. 



How do micro-organisms gain entrance into the body? 



Through the respiratory passages, the digestive system (espe- 

 cially the pharynx), wounds of the skin (especially abrasions), 

 through the generative organs, by insects, etc., and in some cases 

 from mother to foetus. 



What causes them to multiply? 



Heat and moisture in the presence of decomposable organic 

 matter are the main factors, especially when the surroundings are 

 neutral, slightly alkaline in reaction, or in some cases very 

 slightly acid. 



