Nature of Disease. 3 



up of anv chang-e of structure or modification of function which 

 may impaii' this harmony and adaptabiUty to cellular or bodily 

 surroundings. And individual diseases may then be understood as 

 including- special groups of such modifications of structure and 

 function, these groups varying in the isolated afifections in type, 

 distribution and number.] The processes which go to make 

 up a disease are not fundamentally dififerent from the physiological 

 processes, are not features foreign to the operation and structure 

 of the healthv bodv. but are to be directly referred to these ; the only 

 difference being that in disease they manifest themselves in a site, 

 at a time or in a degree other than in the normal state of the body. 

 Pathological processes may therefore, as by Mrchow, be con- 

 sidered as heterotopic, heterochronic and heterouictric physiologi- 

 cal processes (^repos, another; 3 T6iros, place; xp^^o'^^ time; /x^rpov, 

 amount). As an illustration: a h?emorrhage into the ovary, caused 

 by the bursting of a follicle and ovulation, is normal, but a 

 haemorrhage into the brain is abnormal ; unconsciousness in sleep 

 is normal, but at an unusual time and in pronounced degree, as in 

 swooning, is pathological. Almost invariably physiological ana- 

 logies are to be found, in comparison with which the alterations of 

 disease are manifestly but quantitative variations or variations of 

 place and time. The gastric mucous membrane, when the stomach 

 is full and engorged during the process of digestion, is very full of 

 blood and red ; in another part of the body, as the conjunctival 

 mucous membrane, this same redness and congestion would be 

 pathological. The endometrium normally sheds epithelial cells and 

 leucocytes in the lochial secretion in considerable numbers after the 

 removal of the placenta ; were this not merely temporary but of per- 

 manent duration the condition would constitute a pathological one, 

 a catarrh. In the tumors or pathological new growths, which are 

 apparently so foreign to the general organism, there are to be found 

 only the same tissue elements as belong to the normal body, which 

 however possess a power of growth which is abnormal. Even the 

 phenomena of death have their physiological counterpart, as in the 

 mummification of the umbilical cord. 



The various pathological processes may be classed as follows : 

 (i) Anatomical-pathological processes (gross pathological-ana- 

 tomical or pathological-histological) : Here are included all 

 changes of structure or lesions whether of the gross organs or 

 of the tissues and cells, as lesions of continuity of the skin and 

 musculature (wounds), changes in consistence (as cerebral soften- 



