CHAP. xvm. VACCINATION A DELUSION. 



Again, if the very limited and imperfect vaccination of 

 the first quarter of the century is to have the credit of 

 the striking reduction of small-pox mortality that then 

 occurred, as the Royal Commissioners claim, a small 

 deficiency in the very much more extensive and better 

 vaccination that generally prevailed in 1871 cannot be 

 the explanation of a small-pox mortality greater than in 

 the worst years of London when there was no vaccina- 

 tion. Partial vaccination cannot be claimed as produc- 

 ing marvellous effects at one time and less than nothing 

 at all at another time, yet this is what the advocates of 

 vaccination constantly do. But on the sanitation theory 

 the explanation is simple. Mercantile seaports have 

 grown up along the banks of harbors or tidal rivers 

 whose waters and shores have been polluted by sewage 

 for centuries. They are always densely crowded, owing 

 to the value of situations as near as possible to the ship- 

 ping. Hence there is always a large population living 

 under the worst sanitary conditions, with bad drainage, 

 bad ventilation, abundance of filth and decaying organic 

 matter, and all the conditions favorable to the spread of 

 zymotic diseases and their exceptional fatality. Such 

 populations have maintained to our day the insanitary 

 conditions of the last century, and thus present us with 

 a similarly great small-pox mortality, without any re- 

 gard to the amount of vaccination that may be practised. 

 In this case they illustrate the same principle which so 

 well explains the very different amounts of small-pox 

 mortality in Ireland, Scotland, England, and London, 

 with hardly any difference in the quantity of vac- 

 cination. 



The Royal Commissioners, with all these facts before 



