APPENDIX E. cxliii 



Cerebro-spinal meningitis is believed by many to be only 

 a modified form of typhus \ though this is more certainly 

 the case with the plague, in which the typhus poison is 

 evolved in its severest form. Undoubtedly contagious, 

 though formerly believed to be infectious, in the very highest 

 degree, Dr. Gavin Milroy says : ' The whole history of 

 medical opinion on the subject of the plague affords one of 

 the most remarkable instances on record of fanciful specula- 

 tion taking the place of sober and careful inquiry/ And 

 then he adds : ' That the plague has frequently become 

 developed de novo, and quite independently of any antecedent 

 infection, cannot be doubted. The recent outbreak at Ben- 

 gazi, on the Barbary coast, only confirms previous testimony ; 

 and as this outbreak occurred after many years' disappear- 

 ance of the pestilence in that place, as well as throughout 

 Egypt and Turkey generally, no other interpretation is 

 possible. Then, as on many other occasions, the disease 

 sprung up amongst want, wretchedness, and squalor, and its 

 true nature was not recognised for many weeks, in con- 

 sequence of its close resemblance to ordinary typhus, to 

 which it seems to be nearly allied'-.' 



Now the remaining members of the group of specific in- 

 fective diseases are varicella, hooping-cough, measles, scarlet 

 fever, and small-pox. The knowledge which we possess 

 concerning the mode of origin of these otherwise than by 

 infection, is almost nil. They differ amongst themselves, it 

 is true, as regards their degree of infectiousness; but, as 



^ Doubts, however, are entertained on this subject. (See Mr. Rad- 

 cliffe's article in Reynolds's ' System of Medicine,' vol. ii.) 



^ ' Transactions of the Epidemiological Society,' vol. v. p. 1 74. This is 

 generally the rule with regard to epidemics. They occur mostly at 

 times when other ordinary or non-specific affections, to which they are 

 most closely related, are prevalent. And during the period of their 

 decline, the more virulent epidemic forms of the affection again seem to 

 lapse into more ordinary and non-contagious forms of disease. 



