548 



WALDO SHUMWAY 



produced in thyroid fed individuals. Records were also kept 

 for the purpose of comparison with the effects produced on the 

 division rate. A summary of these reduced to five day averages 

 is given in table 20 for the control, a thyroid line. The results 

 are similar to those obtained in the other two races and it will 

 be noted that the percentage increase produced by the thyroid 

 is again 65 per cent. A graph (fig. 6) comparing the life his- 

 tories of the thyroid and control line illustrates how closely the 

 control life curve follows that of the control, points of high and 

 low rates of division occurring simultaneously notwithstanding 

 the fact that at these points the thyroid line is many generations 

 older. 



TABLE 20 



Race C. Average daily division rate re-averaged by five day periods 



Percentage increase produced by thyroid feeding, 65 per cent. 



