EFFECTS OF THYROID ON PARAMAECIUM 



537 



TABLE 1 

 Race A. Experiment 1. Daily division rate averaged by five day periods 



from the freshly dissected glands of ten rabbits macerated and 

 mixed one part to two parts boiled tap water. The emulsions 

 were kept in a refrigerator at about 10°C. and used during period 

 7, in the proportion 2 drops to 2 drops of the control hay infu- 

 sion. A second source, b, was from twenty rats similarly pre- 

 pared and used during period 8, as above and during periods 

 9-12 in the proportion i drop to 4 drops of hay infusion. The 

 third source, c, was from nine rabbits prepared and used as above 

 during periods 13-15. The thyroid and thymus emulsions were 

 prepared similarly from the same animals and were kept and 

 used under identical conditions. After it was evident that the 

 thyroid line was dividing more rapidly than the control (an ef- 

 fect not produced by the thymus) a line was extracted from the 

 thyroid treated one and returned to control medium in which 

 it returned to the average division rate shown by the control 

 line. 



TABLE 2 

 Race A. Experiment 2. Daily division rate averaged by five day periods 



