EFFECTS OF THYROID ON PARAMAECIUM 



543 



The experiment was unfortunately interrupted during period 6, 

 when I was called out of town. During this period the lines were 

 kept in hay infusion and not isolated daily. Table 12 contains 

 the daily division rate averages by five day periods. 



It will be seen from these figures that all the lines divided 

 more rapidly than the control, with practically no differences 

 between them. This experiment is the only one giving such a 

 result and by consulting the life history of the B race, figure 2, 

 it will be seen that the race is passing through the low point of 

 a rhythm. 



TABLE 13 

 Race B' . Experiment 2. Daily division rale averaged by five day periods 



In order to secure a more crucial test it was determined to 

 keep the experimental lines in the gland suspension alone, i.e., 

 without tjie addition of hay infusion. Experiments were per- 

 formed on seven lines, using the following glands : thyroid, thy- 

 mus, pancreas, spleen, ovary, suprarenal and pituitary bodies, 

 with the result shown in table 13. 



Under these conditions the thyroid line alone survived after 

 a few days treatment, presenting on the contrary active indi- 

 viduals at all times and a division rate consistently a little 

 higher than the control. In order to discover whether this effect 

 was permanent the thyroid line was continued from this time on 

 till January 26, 1915, when it died out in the 101st generation 

 since conjugation, on the same day on which the control line 

 died out. The five day averages of the daily division rate are 

 shown in table 14. Figure 4 shows graphically the life history 

 of the control and thyroid lines during this period. The close 

 similarity of the two curves is worthy of mention. It will be ob- 



