152 The E eolation of Medical Science. 



whole duty to his patients. We now know that diseases, 

 .like everything else, are relative. There are no hard and 

 fast lines of symptoms to any disease. We have found that 

 the microbes do not directly cause the symptoms in a con- 

 tagious disease, but the poisons they ])roduce. These 

 poisons we call ptomaines. Just as a small dose of whiskey 

 or morphine will produce light symptoms, so a small dose 

 of ptomaines will do the same. As the system can become 

 accustomed to whiskey and morphine, so that large doses 

 are scarcely able to produce any symptoms, so it can become 

 accustomed to the ptomaines of disease. As the microbes 

 cannot develop unless the ptomaines seriously affect our 

 bodies, to become used to their poisons is to be able to re- 

 sist them. This is how vaccination acts. It makes your 

 system used to the ptomaines of smallpox, so that the 

 germs of that disease find it difficult or impossible to grow 

 in you. This is why one attack of a contagious disease 

 makes us less liable to take another.* This is why, of ten 

 persons exposed, only one seems to take the disease. 

 Notice, I say seems to take it, for more people take con- 

 tagious diseases than we think. Doctors not abreast of the 

 knowledge of the last ten years do not know this, and take 

 light cases of scarlet-fever, measles, smallpox, etc., ft)r 

 simple colds, or fits of dyspepsia, and foolishly treat them 

 as such. Scarlet-fever, and the rest of these diseases, exist 

 in all degrees of seriousness, from a simple headache to the 

 worst anginal types. They show no eruption, nor other 

 sign, and yet are as certainly scarlet-fever as if they did. 

 Measles may exist merely as watery eyes and impaired ap- 

 petite. The victims never dream of their having such dis- 

 eases. 



The last decade lias also shown us that diseases have a 

 selective affinity for certain parts of the body, and the 

 name given to the disease will be no criterion as to its 

 nature. What we call Bright's disease is sometimes 

 measles, sometimes scarlet-fever, sometimes snuxllpox, 

 sometimes consumption, sometimes immoral diseases th;it 

 have centred their forces in the kidneys because they are 

 the weak part of the ])atient's organism. A\'hat we call 

 pneumonia, diphtheria, rheumatism, pericarditis, endocardi- 

 tis, meningitis, i)lt!urisy, and all other local affections, may 



* Ddctor (Iradle's (ieriii Theory of disease, p. \'>\; V. S. Agricult. Report, 

 18S1-S2, !>. L-XJit. 



