6 RECOVERY FROM DISEASE 



when the reserve forces of the patient have been brought into 

 action, with the result that the immunity rises (from d to e). 

 Somewhere during this rise (not necessarily or probably at its 

 commencement) the contest turns in favour of the host ; the bacteria 

 are rapidly destroyed, and the disease is cured. Usually, but not 

 necessarily, there is a rise to a level higher than the previous 

 normal one (e to/), of longer or shorter duration, and then a rever- 

 sion to the normal g. If exposure to cold again takes place, a 

 fresh infection may now occur. 



Now it must be emphasized that natural recovery from disease 

 only takes place in virtue of an acquisition of immunity to the 

 infecting agent, and in no other way ; and, further, that, except in 

 a few instances, medical treatment simply aims in aiding this 

 phenomenon. If we exclude the various sera and vaccines, there 



FIG. i. 



are but two therapeutic agents which have a direct curative effect 

 mercury in syphilis and quinine in malaria. 1 In these diseases 

 the physician can apply a direct remedy, but in other cases the 

 aim and object of treatment is to support the patient's strength 

 until the natural development of acquired immunity takes place, 

 and in some cases to aid this development by certain empirical 

 means. It is found that all agents which tend to improve the 

 general vitality and facilitate the performance of the normal physio- 

 logical processes have this action ; hence the importance of suitable 

 food in amounts and at intervals suited to the patient's com- 

 plaint, of fresh air at a proper temperature, of the removal of 

 pain, and other symptoms which tend to impair the patient's 



1 Arsenic and some other drugs in the treatment of various protozoal 

 infections (trypanosomiasis, etc.) may also be included. It is interesting to 

 notice that all the diseases directly combated by simple means are protozoal 

 in origin. 



