no Mr. Gwvther on the 



In Table III. I have formed the proportion of the death 

 rate from small-pox at the several ages to the death rate at 

 all ages over the same period of time ; we there see that, 

 besides the maximum proportion at the ages under five 

 (which has been diminished), there is a second maximum 

 between the ages of 20 and 25. This appears from this 

 table to have been increasing, but the increase is not more 

 than would be accounted for by the diminution of the 

 infantile rate. 



If we pass beyond the age of 35 the increase of the death 

 rate is obviously an actual increase. 



To account for this it is in the first place obvious from 

 such statistics as I have quoted from Dr. Mc.Vail's paper, 

 that small-pox epidemics gave a considerable, if not com- 

 plete, immunity to those who passed safely through one or 

 two of them — a more lasting immunity than any that can 

 reasonably be claimed from vaccination. If our record 

 went further back we could gauge the effect of this most 

 accurately. If this is, as seems to be the case, not an 

 efficient reason to account for the rise of adult death rate 

 from small-pox, and it is claimed that small-pox has 

 increased in virulence (and there appear to be other 

 than the statistical reasons for imagining this to be the 

 case), the effect of this claim is to make the diminution 

 in the death rate of early years more marked. 



All the consequences of these hypotheses can only be 

 truly estimated by the physician, and so I proceed with the 

 discussion of the statistics. 



In Table IV. I have calculated the ratio of the death 

 rate of males to females at the several ages during the 

 periods which I have been considering. 



From this we see that up to the age of 20 the inci- 

 dence upon the two sexes has been constant and practically 

 identical. Beyond that age the disease has fallen consider- 

 ably more heavily upon the males, the ratio being fairly 



