CLASSIFICATION OF MICROORGANISMS 81 



arthrospores have been observed. These are formed usually 

 by aerial hyphaB which are thrown up from the surface of the 

 medium upon which the organism is growing and break up into 

 segments which resemble bacilli. The term Streptothrix is some- 

 times used as synonymous with both the terms Nocardia and Ac- 

 tinomyces, but not correctly, as the name Streptothrix was, as 

 long ago as 1839, used for a genus in a wholly unrelated group 

 of fungi. Actinomyces includes those types which show true 

 branching and in which spore formation has not been observed. 

 Probably Nocardia and Actinomyces represent but a single genus. 

 In addition to the forms here given, several other genera have 

 been recognized by various writers, but are of no importance to 

 the veterinarian. 



Thiothrix includes all thread-like bacteria which possess no 

 sheath and whose cells contain sulphur granules. Conidia or 



A 

 Fig. 47. A, Beggiatoa (after Winogradsky) ; B, Thiothrix (after Ellis). 



arthrospores are produced at the ends of the threads. This genus 

 is of little importance. 



Beggiatoa. This includes all those forms in which the cells 

 are surrounded by a sheath and contain sulphur granules. 



In addition to the names of the genera given above, a large 

 number of physiologic and pathologic names have been given. 

 For example, Streptococcus pneumonia is frequently referred 

 to as the pneumococcus. This is not in any sense a scientific 

 name, but simply a convenient term for common designation. 

 Other examples of similar type are gonococcus for the specific 

 cause of gonorrhea, meningococcus for the organism causing 

 epidemic cerebrospinal meningitis, and urobacillus for organisms 

 causing certain ammoniacal fermentations in urine. Such ex- 

 amples might be multiplied indefinitely. 



