EFFECTS OF THYROID ON PARAMAECIUM 



545 



TABLE 15 



Race B'. Experiments with iodothyrin. Average daily division rate averaged 

 again by five day periods 



seen that the iodothyrin produced no effect at a time when the 

 thyroid treatment brought about an increase of 0.65 divisions 

 per day. 



Other experiments were conducted with weaker solutions of 

 the iodothyrin which gave essentially the same results. It hav- 

 ing been suggested that boiling the thjo-oid would test the ques- 



TABLE 16 

 Race B'. Experiment 4. Daily division rate averaged by five day periods 



tion as to whether the effects produced were due to an hor- 

 mone, experiments along this line were begun. A 2 grain tablet 

 of thyroid substance was boiled for an hour in 100 cc. of spring 

 water and filtered. The residue was evaporated by slow drying. 

 Approximately 2 mgm. of the dried substance was mixed in 

 2 cc. of spring water to make a culture medium in which a line 

 of Paramaecia was maintained for five days by the usual 

 method. Another line was similarly treated with the filtrate 

 (thyroid bouillon). The results are shown in table 16. 



TABLE 17 

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



