No. 630] 



III' M A V MORTALITY RATES 



35 



supply and the like, or force pregnant women to slave 

 over washtub or sewing bench that they may live, will 

 find themselves irrevocably indicted for the wanton and 

 wilful slaughter of innocent babies. 



V 



We come now to the final stage in this study. Having 

 arranged so far as possible all causes of death on an 

 organological base, it occurred to me to go one step fur- 

 ther back and combine them under the headings of the 

 primary germ layers from which the several organs de- 

 veloped embryologically. To do this is a task of consid- 

 erable difficulty. It raises intricate, and in some cases 

 still unsettled, questions of embryology. Furthermore, 

 the original statistical rubrics under which the data are 

 compiled by registrars of vital statistics were never 

 planned with such an object as this in mind. Still the 

 thing seemed worth trying because of the evolutionary 

 interest which would attach to the result, even though it 

 were somewhat crude and in respect of minor and insig- 

 nificant details open to captious criticism. 



In Tables XII and XIII the death rates of Tables I to 

 IX are subsumed under the three captions, ectoderm, 

 mesoderm and endoderm, according as the organ con- 

 cerned developed from one or the other of these germ 

 layers. It will be necessary, however, before presenting 

 the tables, to set forth in detail how the figures they con- 

 tain were made up. 



A. Ectoderm.— Under this head were placed first, in 

 making up Table XII, the totals of Table VII (the nerv- 

 ous system and sense organs), and Table VIII (the skin). 

 To the sum obtained by adding these totals together 

 was added (a) item 39 (cancer of the buccal cavity) from 

 Table VI, on the ground that the lining of the buccal 

 cavity is ectodermal in origin; (b) 0.30 of the rates under 

 item 41 (cancer of the peritoneum, intestines and rectum). 

 The point here was that the lining epithelium of the rec- 

 tum is derived from ectoderm. The cancer rates for 



