450 



ON INCREASE IN SIZE 



[PT. Ill 



The lower part of the abdomen becomes more prominent towards 

 the end of the foetal period, due chiefly to the rapid expansion of 

 the intestines at this time. The pelvis and lower extremities do not 

 reach their greatest relative size until early adult life, although the 

 upper extremities have reached their maximum relative size at birth. 

 It may also be noted that the organs lying dorsal to the body axis 

 grow at first far more rapidly than those ventral to the body axis, for, 



20 40 60 80 100 120 140 160 180 200 220 240 260 280 



Days 



Fig- 59- 



while in the 2nd month the former are three times the size of the 

 latter, at birth they are equal, and in the adult the latter are six 

 times the size of the former." Jackson's data on the growth of such 

 organs as the suprarenal gland should also be of much service to 

 chemical embryologists, and his paper as a whole is of great value, 

 as it summarises the results of all the earlier workers — Welcker & 

 Brandt; Brandt; Anderson; Lomer; Meeh; Liman; Thoma; Oppen- 

 heimer; Collin, Lucien & Beneke; Devergie; Schmidtt and Elsasser. 

 The general results of all the workers who have occupied themselves 

 with the weights of foetal parts are tabulated in Table 59, which 

 gives the point in development at which the maximum percentage 

 of the total body-weight is reached, what that percentage is, what it 

 becomes at birth and what eventually it is in the adult animal. 



