98 Course of Disease. 



that] organ; if, however, a number of organs are involved and 

 their functions interfered with, and if the general economy is ap- 

 parently affected, the condition is spoken of as a general disease 

 or a disseminated (generalized) disease. (Examples of general 

 disease are met with in such alterations as provoke general 

 metabolic disturbances and abnormalities in the composition of the 

 blood. Formerly the term constitutional disease or dyscrasia, de- 

 composition of the blood, was used in this connection.) Funda- 

 mentally there is no distinction in these terms, but as a rule the 

 term dissemination has special reference to a multiplication of 

 local lesions, to an extension of the causes of the disease to a 

 number of situations where new foci of the same type appear, or 

 to a reaction of a functional disturbance of one organ upon the 

 rest of the system. For example, a prolonged disturbance of the 

 function of the kidneys will give rise to a disturbance in the 

 cardiac action and retention of harmful products of metabolism ; 

 or, as in the case of tuberculosis, the infectious agencies pass 

 from the original local focus into the lymph and blood, extend by 

 direct growth into the surrounding organs, and in various scat- 

 tered foci in the body to which they have been conveyed ; the dis- 

 ease thus becoming disseminated and generalized. Some affec- 

 tions, on the other hand, at first manifest general symptoms 

 (fever), later, however, showing distinct evidence of their purely 

 local type. Variations in the course of disease may also depend 

 upon the predisposition characterizing the animal species in ques- 

 tion, as, for example, is seen in case of glanders in field mice, an 

 acute septicemic affection, in contrast to the same disease in 

 horses, where it is usually a chronic local affection, gradually ex- 

 tending through the system. 



The local lesions which first arise from the operation of a 

 pathogenic agency are known as primary lesions, those which fol- 

 low as secondary. The action of such an agency may be confined 

 to one locality, the lesions disappearing after its removal, as in 

 case of corrosion, heat action or traumatism. The generalization 

 usually depends directly upon the spread of the pathogenic influ- 

 ences through the body, and may therefore take place (i) by 

 continuity and contiguity of the tissues (per contimdtatem, per 

 contiguitafem) , (2) by the blood or lymphatic tissues {hcematogen- 

 oi!S, lymphogenous), and (3) as already referred to, the func- 

 tional interdependence of one organ upon the others may, in case 

 of disease at one point, lead to further change in other parts of the 



