290 



ELEMENTS OF BIOLOGY 



in general, is increase in size as a result of metabolism. It is most 

 rapid in relation to the size of the organism in early embryonic 



600 % 



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400 % 



300 0/9 



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100 o/o 



ISO % 



100 °/o 



MONTHS I 23456769 10 r£AfiS I Z 3 4 b 6 7 8 9 10 II 12 13 14 IS 16 17 10 1$ 20 21 22 23 24 29 



A. B. 



Fig. 194. — A, graph showing the decrease in rate of weight gain in the human 

 embryo from the fourth lunar month of development until birth. B, graph showing 

 the decrease in rate of weight gain in humans from the first to the twenty-fifth year. 

 (After Minot.) 



life, and declines, with fluctuations, as development proceeds (Fig. 

 194). In Man growth ceases altogether when all the principal tissues 

 are completely differentiated. In animals that reproduce agamically, 



