Experimental Study of Growth 



241 



hatching (when the records begin in the table) there is a steady 

 and rapid growth due to the inhibition of water. The dry sub- 

 stance even decreases during this time. Then follows a period 

 when the dry substance increases enormously, so that the percent- 

 age of water falls, but nevertheless a great amount of water 

 continues to be absorbed, and is mainly responsible for the in- 

 crease in size. 



The next table gives results obtained by Potts for the growth 

 of the chick: — 



Here we see that the percentage of water falls in later stages, and 

 the increase in weight must be due in a greater degree to the 

 assimilation of the materials of the yolk. Nevertheless, there 

 must be a continuous absorption of water from the albumen or 

 w^hite, for, although the percentage sinks, the amount of water 

 is continually greater. 



Similar results have been found by Fehling for the human 

 embryo as shown in the following table : — 



