598 



Lorande Loss Woodruff. 



nated this Culture A, although but one culture of this species 

 has been studied. The culture was put at once on a grass- 

 infusion diet and continued on the same during its life. 



From Diagram V it will be seen that the rate of division for the 

 first three periods was very close to one division per day. On 

 June 25, which fell just at the end of the third period, I moved the 

 culture from Williamstown, Massachusetts, to New York City. 

 The greatly increased division-rate, which appeared in the follow- 

 ing period and was augmented in the period succeeding that to 

 almost two and one-half divisions per day, is difficult to account 

 for with any certainty. The jolting which the animals received 



Gastrostyla steinii, Culture A. — {Ten-day Periods.) 



June 1904 July 



Nov. 



Complete history of Gastrostyla steinii, Culture A, from start (May 28, 1904) to its 

 extinction (December 5, 1904) averaged for ten-day periods. Method of plotting the same as in 

 previous diagrams. 



on the trip to the city, the change to city tap-water, the change 

 of grass with which the infusion was made, and the increased 

 atmospheric pressure are prominent among the factors which 

 may have tended to stimulate the fission-rate. Further, the 

 treatment of the culture was exceedingly uniform beginning with 

 its location in New York as I wished to see if the minor fluctua- 

 tions in the division-rate, so prominent in the earlier cultures, 

 could be modified or entirely eliminated by still more stable 

 conditions. Again, I employed this culture as a ''control" for 

 certain experiments on the effects of salts on the division-rate and 



