346 Human Physiology. 



epidemic, nine-tenths of the mortality is among the classes who 

 enjoy least of the conditions of health, and are most exposed 

 to the general causes of disease; and it is observed that the 

 most fatal epidemics but slightly disturb the general averages 

 of mortality that those who are carried off by them are mostly 

 such as would have soon died of other diseases. 



Constitutional diseases are generally hereditary, and heredi- 

 tary diseases are preventable. Gout and cancer, scrofula and 

 consumption, run in families ; but why one should have painful 

 swellings of the joints, liable to be transferred to the stomach 

 or the heart why the breast, or stomach, or womb of another 

 should take on the morbid and malignant growth of cancer 

 why tubercules should form in the lungs or the glands of the 

 mesentery and destroy the power of forming blood or aerating 

 it, and so produce a slow and wasting death, human science is 

 powerless to explain. The causes, in most cases, are evident 

 enough ; the phenomena we know too well but of the nature 

 of the diseased action we know very little. And in some cases 

 nature seems at fault in her efforts to expel disease or the 

 causes of disease. In cancer it seems as if all the bad matter 

 of the system gathered to one point, and there set up a false 

 and destructive action. This action may be modified, sus- 

 pended, sometimes reversed. Surgery cuts away the diseased 

 part, but where the diseased tendency exists it is very liable to 

 recommence its action. In consumption of the lungs, where 

 the matter of disease gathers in lumps called tubercles, there is 

 an effort to cast out the diseased matter. The tubercles sup- 

 purate, and are discharged. In rare cases, where small portions 

 of the lungs are involved, this is a process of cure. Generally 

 the strength is insufficient, and vital organs fail to relieve them- 

 selves because of their vitality. This class of diseases, and 

 especially those of the second order, cause a great mortality. 

 In 1865 the deaths from constitutional diseases in England 

 were 88,504; from consumption, 53,734- And tubercular 



