b-i VETERKXAR-i- PATIIOLUGY. 



lil-)erated into the surrounding' media. The cheniic composi- 

 tion of bacterial toxins is unknown. They are \'ery similar in 

 man\- respects to enzyms. They are specific, i. e., a given 

 organism always produces a definite toxin. According to 

 Ehrlich bacterial toxins are composed of two combining 

 groups, one the haptophore which combines with the receptors 

 of the animal cells and form a medium through which the other 

 group, toxciphore, acts. Thev are the principal product in 

 some infection, e. g. tetanus. (Infection is the invasion into a 

 living bodv of pathogenic micro-parasites, and the sum total 

 of the disturbance produced by their presence in the bod}-). 

 During infection the buch' attempts to neutralize bacterial 

 toxins bv the production of a siil:)stancc termed an antitoxin. 



2. Endotoxins are poisonous chemic products formed and 

 retained within the bacterial body. They become liberated only 

 when the bacteria are destroyed and disintegrated. Although 

 the chemistry of endotoxins is not known, thev are probably 

 constant in composition and produce specific symp>toms in in- 

 fected animals. The animal body does not produce antibodies 

 that neutralize enddtoxins, Ijut (ipsr)nins, l:)actericidal sul)- 

 stances and agglutinins are produced in the tissues of animals 

 immunized tn endntdxins. Endritnxins are the principal in- 

 jurious substances produced hv |)\-ogenic Cocci. Bacterium 

 Tuberculosis, the organisms causing glanders, pneumonia, and 

 other specific infections. 



?>. Ilacterial proteids are insoluble nitrogenous constit- 

 uents of the bacteria cell protoplasm. Thev are not well under- 

 stood. (See insert No. 3.) 



ANIMAL PARASITES. 



The animal parasites, capable of producing disease in an- 

 imals, are (piite numerous and re])rcsent tlie following 1)ranches 

 of the animal kingdom: — protozoa, helminthes, and arthropoda. 



y*^/^^r^ 



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r'- . ''i 



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Fi.g, 3 0.— piroplasnia Biffeniinuni in the rcrl bl"iod cnrpuscle». 



