308 Dr Robert E. Brown on the 



their former constitutions are destroyed, in order to make way for 

 a state of body more in accordance with the amount and the arrange- 

 ment of the forces existing m. their new place of abode. In the same 

 way natives of a tropical country, on passing into a cold one, are 

 peculiarly subject to various disorders. In certain localities again, it 

 may happen, that the different forces exist in such a state of ac- 

 tivity, either absolute or relative, or that they are subject to such 

 variation, that the organisation of living beings cannot arrive at per- 

 fection, or that it has a tendency to degenerate into abnormal states. 

 In accordance with this we find that there are some countries in which 

 "human litis, at least, hardly arrives at perfection, and in wliich it 

 has a tendency to assume certain actions incompatible with health. 

 We see these circumstances as strongly instanced on portions of the 

 west coast of Africa as anywhere else, in the miserable physical 

 development of the natives, and in the tendency which the native, 

 and still more, the European inhabitants have to become diseased, 

 and to die. That this comes either from the absokite activity of 

 the forces, or from their relative proportions in the place, seems to 

 be indicated by the fact, that it is chiefly in one certain mode 

 that the functions of human bodies are affected, and the endemic 

 disease of the place can only be supposed to originate in an endemic 

 activity or proportion of the forces of the place. In different sea- 

 sons of the year, ao-ain, and in the same place, — and again at certain 

 times, independent of the seasons and the locality, and apparently 

 irregular and unfixed, tiie relative activity of the forces vary, and, 

 therefore, we should expect that a tendency to a certain abnormal 

 mode of action should be developed among the inhabitants. Ac- 

 cordingly, we find that at certain times and seasons, great numbers 

 of people have the functions of their bodies disordered in some de- 

 finite manner, and, in almost all, the tendency toward that disor- 

 dered mode of action may be more or less observed — in other words, 

 we have an epidemic disease. Lastly, it is perhaps conceivable that 

 at any time the vital forces of individuals may vary from causes 

 affecting them alone, and the just proportion between these and the 

 external forces may thus be lost, either throughout the whole sys- 

 tem, or in particular parts of it, in which case diseases, differing in 

 character according to the degree or the mode in which this takes 

 place, will befall them. How far all these abnormal actions of life 

 correspond to the changes which certainly do take place in the rela- 

 tive proportions of the various forces, and which ought, on the views 

 given above, to produce these or some other similar effects, experi- 

 ment and observation must determine. 



We have already seen, that in different regions of the earth the 

 condition of health results although different proportions between the 

 several forces exist in them. This diversity, however, as we formerly 

 indicated, can hardly extend to the proportion between the two classes 



