The Life History of Tillina Magna 407 



The effect of the sugar solution was to lower the vitality, to 

 produce abnormalities, and finally to cause death. 



The tap water, likewise, was found not to be a successful me- 

 dium, though the detrimental effects were not as quickly noticed 

 as those due to the sugar solution. The comparison of the records 

 for B3 and B4, the non-stimulated lines, with those of B7 and B8 

 show the effects of the water medium at a glance. 



B3 B4 By B8 



February 27 2 o i i 



February 28 2 2 o 2 



March 1 2 2 3 i 



March 2 2 2 o o 



March 4 I 2 o o 



The effects of the pancreas, potassium phosphate and beef ex- 

 tract are seen best in Diagram IV, where the histories of each treat- 

 ment together with the non-stimulated cultures, are shown. Of 

 the three curves, the one indicating the pancreatic treatment 

 shows the most abrupt changes or greatest fluctuations. All 

 three curves show a decrease in vitality during the 12th period, 

 The pancreas series recovered most quickly from the depression, 

 changing from a rate of i.i divisions per day in the 12th period, to 1.6 

 divisions in the 13th period. During the following period, it fell 

 again to .9 only to rise again to 1.2 in the 15th period, and then to 

 die out quickly in the 17th period. 



The potassium phosphate series is much more gradual in its 

 rises and falls. The curve is very much like that of the main 

 culture. It maintains a slightly higher average, however, through- 

 out its history. 



The history of the beef series shows the greatest actual effect. 

 The division rate is higher than normal throughout the life of the 

 culture. That one treatment was not sufficient to carry the series 

 along, is shown by the fact that the lines re-stimulated on the 17th 

 period lived while the lines which received but the one initial 

 stimulus died during the 20th period. Though the main line lived 

 as long as the re-stimulated series, yet it^ average rate of division 

 was lower, and the general condition of the individuals was much 

 poorer and weaker. The beef extract undoubtedly had a strength- 

 ening effect. 



