538 



WALDO SHUMWAY 



Experiment A 2 was commenced while the previous experi- 

 ment was yet in progress, to discover whether other individuals 

 of the A race were susceptible to the thyroid effect. An individual 

 was selected from the A line and allowed to divide until there 

 were twelve cells of the same generation. Four of these were 

 continued as a control line, four treated with thyroid and four 

 with thymus. 



TABLE 3 



Race A. Experiment 3. Daily division rate averaged by five day periods 



Experiment A 3, performed after a railroad journey to Woods 

 Hole and a change to the local tap water, was continued for only 

 one period owing to the difficulty of keeping fresh tissue, in this 

 case from cattle glands supplied me through the kindness of Dr. 

 Gudernatsch. 



TABLE 4 



Race A. Experiment 4- Daily division rate averaged by five day periods 



Experiment A 4, performed at the same time as A 3 and 

 under the same conditions, had as control a line which had been 

 treated with thyroid for nine periods and thereafter maintained 

 in the control medium for eight periods. 



TABLE 5 

 Race A. Experiment 5. Daily division rate averaged by five day periods 



Experiment A 5 was carried on during a depression period 

 at a time when the control line was reduced to two individuals. 



