94 PRINCIPLES OF VETERINARY SURGERY 



Spirilla. — The spirillum is a bacterium shaped like a cork- 

 screw. Some are short, like bent bacilli, while others are 

 long and slender. They appear in both the flagellated and 

 unflagellated forms. 



« b 



Fig. 3. 

 a, Vibrio ; b, Spirillum. 



, According to their function bacteria may be divided into 

 the following important classes' 



a. Saprogenic. f. Photogenic. 



b. Zymogenic. g. Pathogenic. 



c. Aerogenic. h. Alkali-forming. 



d. Acid-forming. i. Nitrifying. 



e. Chromogenic. 



a. Saprogenic bacteria are those which produce putre- 

 faction. These bacteria decompose the complex nitrogenous 

 compounds into simpler chemical combinatiq/ns. They trans- 

 form albumen into peptones and then split up the latter 

 into salts, acids and gaseSj and sometimes into very poison- 

 ous alkaloidal compounds called ptomains. Example, 

 bacillus tremulus. 



b. Zymogenic bacteria are those which produce fermen- 

 tation. These micro-organisms possess the power of reduc- 

 ing the complex molecules of non-nitrogenous matter (e. g. 

 carbohydrates) into simple compounds. Examples, bacillus 

 aceticus, bacillus butyricus, etc. These bacteria are of much 

 more importance in the study of chemistry, physiology, and 

 physiological chemistry than in pathology. 



c. Aerogenic bacteria are gas producing bacteria. Dur- 

 mg putrefaction and fermentation various gases are elabor- 

 ated, among which are carbonic acid, hydrogen, hydrogen 

 sulphide, ammonia, etc. Gas production is the property of 

 many bacteria, but the process may continue unnoticed un- 

 less the decomposition is occurring in a confined place — the 



