VII 



THE STAGES OF LIFE AND DEATH 



271 



the foetus as such. The presence of glycogen in the placenta, 

 discovered by (Jl. Bernard, demonstrates that it possesses a 

 glycogenic function similar to that of the liver in the adult. 



In addition to the respiration and nutrition of the foetus, the 

 placenta serves also for the elimination of its waste products, thus 

 performing a function analogous to that of the kidneys. The 

 blood flowing from the venous sinuses of the decidua serotina is 

 indeed rich in broken-down substances from the tissues. 



The active exchange of materials between the mother and the 

 foetus results in a rapid growth of the tissues which is not 

 equalled at any stage of extra-uterine life. Many numerical data 

 of the increase in volume and weight of the human foetus have 

 been collected by Autenrieth, Chossier, Hecker, Hemming, His, 

 Fehling, Toldt, Kolliker, and others. Owing, however, to individual 

 bodily differences and to the difficulties experienced in determining 

 the exact age of the embryo, it has been impossible to obtain the 

 exact curve of foetal development, and we are unable to decide 

 whether there is a good foundation for Sommering's opinion that 

 it takes place by unequal bounds, with pauses and accelerations 

 in the different months of gestation. 



Preyer calculates that the length of the foetus is doubled no 

 less than five times during the period between the fifth week and 

 birth, and its weight from the ninth week till birth increases 

 about 800 times, whereas the length of the body reached at birth 

 is not even quadrupled during the whole of extra-uterine life, and 

 its weight is only multiplied twenty -two times. 



The extremes of foetal growth, which differ considerably 

 according to race and numerous individual factors, are shown by 

 the following table : 



It will be seen from this table that the values for both length 

 and weight vary within somewhat wide limits.' In some cases 

 the foetus may be at full term in spite of insufficiency of weight 

 and length. Ahlfeld saw in 1909 a new-born infant at term 

 which weighed only 1590 grins, and was 44 cm. in length. 



