VETERINARY BACTERIOLOGY 



SECTION I 



MORPHOLOGY, PHYSIOLOGY, AND CLASSIFICATION 

 OF BACTERIA 



CHAPTER I 



INTRODUCTION 



BACTERIOLOGY may be defined as that branch of science which 

 treats of bacteria, their forms, and functions. Since the true 

 bacteria are plants, this science may be considered as a sub- 

 division of the great mother science of botany. Bacteria are 

 the direct or indirect causes of many pathologic conditions in 

 the bodies of animals, their study may accordingly be regarded also 

 as one of the fundamental sciences underlying medicine. 



Certain of the microscopic unicellular animals (protozoa) are 

 likewise commonly considered in a discussion of bacteriology, 

 for some of them are known to cause disease, and have been 

 studied largely by means of the laboratory technic developed 

 by the bacteriologist. There are several other reasons for this 

 inclusion: the dividing line between bacteria and protozoa is far 

 from distinct, and it is impossible to determine in many cases 

 from a superficial examination of a new disease whether it is 

 caused by the invasion of true bacteria or protozoa. Further- 

 more, the line of demarcation between the true bacteria and that 

 group of plants known as fungi (including molds, mildews, smuts, 

 rusts, toadstools, puff-balls, etc.) is very poorly defined. Several 

 of the molds and yeasts are disease producing, and are generally 

 included in a discussion of bacteriology. Certain worms, mites, 



