172 INFECTIOUS AND PARASITIC DISEASES. 



ill-suited to our purpose, which is to direct attention 

 to the more obvious atria, and also to those portions of 

 the body as are most likely to be the primary or initial 

 seat of the various infections. Syphilis well illustrates 

 our aim. Syphilis is a typical inoculable disease, a 

 break in the integument or a mucous surface being 

 required for entrance of the virus. But if we only 

 treated of its portals of entry under lesions of the skin 

 and mucous membranes, data of the highest importance 

 would not be included. Nothing, for example, would 

 be said of the fact that the initial infection is usually 

 found upon the genitalia, not that the infection is 

 hereditary. Hence, the reason for employing a classi- 

 fication apparently illogical. 



The more obvious portals are those easiest remem- 

 bered, and the most practical; and therefore, under the 

 inoculable diseases are placed those which are either 

 contracted through visible lesions, or can be inoculated, 

 although under natural conditions this may not seem to 

 occur;* and under the other divisions are grouped 

 those which experience has taught attack one portion 

 of the body rather than another. Obviously under such 

 a classification, a disease will often be found under two 

 or more heads. 



♦Example: — Small-pox is ordinarily contracted by contact of an un- 

 vaccinated person with a patient or fomites. That it is directly inocu- 

 lable, the earlier practice of variolation, introduced into England by 

 Lady Mary Worthey Montague in 1727, shows. 



