26 CHEMISTRY AND PHYSICS IN RELATION 



impossible to entertain a doubt concerning the cause of the origin and further pro- 

 pagation of a number of contagious diseases. 



PUTREFACTION PROCESSES AS CAUSES OF CONTAGIOUS DISEASES. 



General experience has at length shown us that " the origin of epidemic diseases 

 can often be traced to the putrefaction of a number of animal and vegetable substances; 

 that miasmatic diseases become epidemic where there is constant decomposition 

 of organic matter in marshy, damp districts. And that they also develope them- 

 selves epidemically under similar circumstances after inundations ; besides, in other 

 places where a large number of people are assembled together with little change 

 of air as in ships, prisons, and besieged places, &c. ;* further on, at page 27, the 

 same author observes that " we can never prognosticate the origin of epidemic 

 disease with more certainty, than when a marshy flat has been dried up by con- 

 tinued heat, or when excessive heat follows extensive inundation." 



CONCLUSIONS. 



Here our deduction is fully justified according to the rule of natural inquiry, 

 that in all cases where a process of putrefaction has preceded the first indications 

 of disease, or where disease can be communicated by solid, fluid, or gaseous pro- 

 ducts, and where no more immediate cause can be adduced, the substances or 

 matter in the act of decomposition must be looked upon as the most probable 

 cause of disease. 



POWER OF INFECTION IN WHAT IT CONSISTS. 



The requirement for the capacity of infecting a second individual, is the pre- 

 sence in the body of the latter of a substance which can oppose no resistance 

 either in itself, or through the vital energy in the organism to the causes affecting 

 a change of form and property. If this substance were a necessary constituent of 

 the body, disease must be transferable to all individuals ; if only an accidental 

 constituent, those persons alone would be infected in whom this substance was 

 present in sufficient quantity, and of the characteristic nature. The termination 

 of disease is only a destruction and removal of this matter ; it is a re-establishment 

 of the condition of equilibrium of those causes in the organism which regulate its 

 normal functions, and which had been temporarily suspended. 



A CHALLENGE TO INVESTIGATION. 



Practical medicine will soon decide whether this view be correct or not; and it 

 will then be shown whether there is any actual connection between the relation of 

 arsenious acid to animal membranes out of the body, and their action in certain 

 fevers ; and between the relation of mercurial compounds to animal substances, 

 and their action in contagious diseases. 



If this so-called chemical view do not serve as a guide and director to the phy- 

 sician, after a careful study of the processes of putrefaction of simple and com- 

 pound bodies, and of the materials and causes by which these processes are 

 altered, hindered, or accelerated ; and if a comparison of this with other analo- 

 gous processes in the human organism, be not the means of enlarging his views 



*IEenle, Untersuchungen, p. 52. 



