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then become related agents. Thus, while our tumour is at rest, 

 suppuration might take place in the axillary glands, and the tumour 

 might disappear, while the contiguous parts are running a long 

 course of disease; or, the tumour being at rest, an habitual diarrhoea 

 might occur, and the tumour disappear; or the tumour might re- 

 main at rest until the cessation of the catameuia, and then it may 

 begin to increase in size, become painful, and finally degenerate 

 into cancer; or, by some accident, the tumour in its state of rest 

 may receive a blow; it may in consequence inflame, suppurate, and 

 disappear; or it may become malignant from this cause. This illus- 

 tration is sufficient : the axioms I mean to establish, with respect to 

 the general history of causes in the production of disease, are, 



1st, That every primary, spontaneous, disease is produced by 

 progressive change in the constituents of its seat. 



2nd, That this progression may be interrupted, when the present 

 state ceases to find a causative relation with existing causes. 



3rd, That if the progression of change is resumed, it is because 

 new causes obtain a relation which did not before exist with the 

 constituents of its seat. 



4th t That these new causes may come to produce change in a 

 given seat, either from progressive internal change among connected 

 properties, or from exposure to an external cause which is related 

 with the present predisposition of the seat; these might be 

 complicated. 



5. If then we would trace the history of spontaneous disease, 

 we should indeed, although the general laws are so few, undertake 

 a perplexing inquiry. Say a tubercle forms in the 'lungs: why does 

 it form there? the part, it may be said, becomes thickened by 

 coagulable lymph, which then becomes organized, grows, suppurates 

 imperfectly, &c. Why was the lymph thrown out? from inflam- 

 mation; why did the inflammation occur? excited by cold; how 

 can^e the part predisposed to such a relation with cold ? it has some- 

 how attained such a state. Now my abstract refers to this word 

 ' somehow ;" and if this somehow is to be answered, the only reply that 

 can be given will be found in the above propositions, which I have 

 called axioms. To leave then this subject of the manner in which 

 disease begins, and without taking any further with us the incum- 

 brance of these views, we will simply say, when disease occurs 

 spontaneously without any assignable external cause, that it happens 

 from the development or operation of latent causes, about which we 

 have been of late so busy; and that when disease happens from an 

 external assignable cause, which does not produce the same effects 

 in others, or in the same individual at other times, we will say that 

 a predisposition existed to the operation of such cause, of the 

 nature of which predisposition also enough has been said in 

 the way of indication. 



6. We have assigned in our physiology three sets or classes of 

 properties which concur to constitute an animal, viz. those belong- 

 ing to the vital, the chymical, and the mechanical departments. 



