THK CAVENDISH LKCTURK 



The population has been sensibly growing older ; the persons of 

 reproductive ages have increased by about 3'5 per cent. A certain 

 portion of this is almost certainly due to the survival of weaklings, 

 but a part is also due to the decreased birth-ratr. It is not an 

 easy matter to determine how much is due to each source. But 

 we can show from isolated instances that in many ways medical 

 science has led to a survival of the unfit. I may, perhaps, be 

 permitted to illustrate this matter from one or two concrete cases. 

 The reduction of mortality in child-bed has been very consider- 

 able, especially in cases where operative surgery is needful. A 

 century ago, or at least a century and a half ago, Caesarian section 

 was rare, or at any rate if adopted very doubtful in its success. 

 The result was that an achondroplasic mother rarely survived 

 childbed ; even normal mothers confined with an achondroplasic 

 child much more rarely had a viable offspring. Medical literature 

 and old pathological collections abound in illustrations of how the 

 achondroplasic dwarf failed to survive in the struggle for existence. 

 Many cases were screened under the name of congenita! or foetal 

 rickets in the old theses, and few survived birth. The whole 

 matter has now been so modified by increased surgical skill that 

 we have cases of women in which Caesarian section a[)pears to be 

 the usual method of childbirth — two or three, even five instances 

 in the same woman being on record. The result is that modern 

 pedigrees of achondroplasic dwarfs begin to show descent through 

 the female as well as through the male — an occurrence of great 

 rarity in the older pedigrees. 



As my audience is wholly medical to-night, I throw on the 

 screen one or two photographs to illustrate this point. First we 

 may have photographs of this type of dwarfism (Plate I). it is 

 well represented by those sent me by Major C. H. James, I. M.S. 

 I now give you in a pedigree provided by Professor Nijhoff, 

 the well-known Dutch gynyecologist, an illustration of the heredi- 

 tary character of achondroplasia (Fig. 8). Here is another case. 



