THE CAUSATION OF DISEASE. 2 1 



in any one of the ways just enumerated, it is apt to rapidly 

 implicate the other tissues. Thus, a slight defect in one of 

 the heart-valves may ultimately lead to an altered E of every 

 cell in the body. A leakage in the mitral valves may entail 

 a terrible series of troubles, beginning with an excessive accu- 

 mulation of fluid in the cell-chambers, and leading on to a 

 universal growth of fibrous tissue. Aortic regurgitation, too, 

 may profoundly modify the bodily nutrition by causing the 

 blood to flow in jerks through the capillaries, and thus inter- 

 fering with the proper interchange between the intra- capillary 

 blood and tissues. How soon does kidney disease, again, make 

 its influence felt throughout the body ! The circulatiou of 

 nitrogenous sewage renders the tissues more apt to inflame ; 

 hence the tendency to bronchitis and inflammation of the 

 serous textures. It may be that the circulation of these 

 poisonous matters through the tissues is alone sufficient to 

 excite inflammation, or perhaps the inflammatory process is 

 due to their presence, plti$ something else which could not by 

 itself provoke inflammation. J3e this as it may, inflammation 

 always occurs sooner or later. All the other complications of 

 granular kidney are due to the retention in the blood of these 

 same nitrogenous products. I imagine few will dispute this. 

 The universal mal-nutrition, the disordered digestion, the en- 

 larged left heart, the thickened, contracted and atheromatous 

 arteries, the breaking of blood-vessels whether in the brain or 

 elsewhere, and the paralytic stroke : these are, each and all, 

 links in the same vicious chain. It is interesting to specu- 

 late upon the proper position of these several links, more 

 especially so far as concerns the vascular changes, but 

 whatever their proper place, none can doubt that they all 

 actually are links in the same chain. None can doubt, I 

 say, that a defect in the sewage system may so implicate the 

 vascular system as to lead slowly but surely to a riddling 

 of one of the cerebral vessels, to the flooding of the brain- 

 substance with blood, and to the paralysis of one-half of the 

 body. 



In like manner a defect in the secretory system may 

 work evil by producing a universal modification of cell-E. 

 Suppose, for instance, a digestive juice to be faulty : blood- 



