146 \■E'J'I■:RINAR^■ patikjloc.v, 



cciphvsematous bovis) ; nialionant oedema caused l)y the Bacil- 

 lus I if malignant oedema. 



Sl1ppurati^■e infective inflammation is characterized by the 

 formation of pu.s. The causative bacterial agents of suppura- 

 tirm are designated as pvogenic bacteria or pyobacteria. The 

 following are the most important bacteria of this class; 



Staphylococcus pvogenes aureus. 



Staphvlococcus pyogenes al1)us. 



Sta])h\d(icoccus pvogenes citreus. 



Stre]Dto-coccus pyogenes 



Baccillus pyocyaneus. 

 Factors Concerned in Inflammation. — The animal budy is 

 an intricate mechanism composed of different tissues in \-arious 

 coml)inations. The phenomena of inflammation are the changes 

 that take place in the tissues ])lus the C(inditi(.)ns resulting from 

 those tissue changes, thus including all the changes taking place 

 in the inflammatorv focus. The following are the most impor- 

 tant. 



\\\scuL.\K i>[STi'Ki'..\xci-:s. — Tlicsc are universalh' present in 

 aninipis pnsscssing a \'ascular system, but inflammation, or a 

 conditiiin analagous to it, occurs in the tissues of animals that 

 ha\-e nri vascular system, and in nonvascular tissues of animals 

 that h,a\'e a vascular svstein. Hence ^•ascular changes are not 

 essential m the process. The vascular changes are dependent 

 upon ner\-(ius influence, because the calibre of blood vessels, 

 especially arteries, is controlled In' vasomotor nerves, i. e., vaso- 

 dilatiirs and \-asi>-ci instrictors ; stimulation of the former produc- 

 ing ililatation, of the latter constriction of the vessel. Inflam- 

 matiir\- areas liecome necrotic when dilatation of the supplving 

 arteries and arterioles is inhibited. In experiments in which 

 dilatatiim nf the arterioles takes place the inflammator)- pro- 

 cess is limited and usuallv terminates in recoverv in a short 

 time. Xecrosis usually succeeds inflammation in tissues in 

 wliich communications of the \-asomot(.)r ner\-es ha^•e been de- 

 stroyed. For example, the cubital nerve in the horse probably 

 contains the vascimotor fibres that innervate the vessels of the 

 foot and the median nerve the sensitive fibres that innervate 

 the pedal structures. Median neurectomv is not succeeded bv 

 vascular disturbances, but cubital neurectomy is fre(|uently 

 succeeded by vascular disturbances and excessive exudation 

 that terminates in necrosis followed bv sloughing of the hoof. 



The following vascular changes occur in an inflammatory 

 focus and in the order designated: 



Decreased calibre of the supplying arteries and arteri(_-iles. 



