THE EVOLUTION OF DEATH 



71 



600% 



500% 



sex up to the age of forty years. The vertical lines indicate 

 by their distance from one another what interval is required to 

 permit each time a lo-per-cent. increase of the weight. 



We may proceed further and study growth during the 

 embryonic period. Unfortunately this has not yet been done 

 so thoroughly and exactly as for the development after birth. 

 Nevertheless we can assert now that 

 the growth of embryos proceeds faster, 

 Fig- 35) ill younger embryos, and that 

 in very young embryos the daily in- 

 crease is simply enormous. For, as I 

 have demonstrated on a previous occa- 

 sion, it may reach in very young em- 

 bryos the value of at least 1000 per 

 cent. Professor Donaldson^* of the 

 Wistar Institute has already published 

 more exact data as to the weight of 

 embryos of the white rat. He has 

 collected further data, and we may 

 expect from him a detailed memoir on 

 embryonic growth. He has completely 

 confirmed my result that there occurs 

 an enormous decrease in the rate of 

 growth during embryonic life. These 

 investigations lead us to the conclusion 

 that the diminution in the rate of 

 growth occurs chiefly during the first 

 developmental periods, and that the 

 diminution after birth is very gradual. Hence if we 

 seek for the cause of this diminution, the facts indi- 

 cate that we should investigate the conditions during 

 embryonic life because this is the period of loss We 



400% 



300' 



200% 



100% 



V 



01 23456789 10 



Fig. 35. — Curve of the 

 monthly increase in weight 

 of the human embryo. 



