124 BRUCE D. REYNOLDS. 



(and 7.75 generations) shorter than was the case when no change 

 was made in the environments. It is thus shown that the 

 absence of light does affect, either directly or indirectly, the 

 physiological constitution of A. polypora. 



(/;.) The Two Lines of a Clone Exposed to Different Temperatures. 



Specimens were exposed for twenty-four hours to temperatures 

 of 36, 35, 30, 28, and 27 degrees centigrade, but in every case 

 death occurred during the period of incubation. However, if 

 incubated for only four hours, the organisms were able to resist a 

 temperature of 36 degrees C. Tests were made to determine if 

 such short exposures to heat would affect the protoplasm enough 

 for it to be detected by the cross-fusion method. No changes of 

 this sort could be revealed; regardless of whether the observa- 

 tions were made immediately after incubation, or twenty-four 

 hours later. 



Attempts to culture A. polypora at low temperatures proved 

 to be more successful. Fifteen degrees centigrade was arbi- 

 trarily chosen as the low temperature environment, while room 

 temperature (21 degrees C.) was used as the norm. A lower 

 temperature was not selected because it was desirable that the 

 organisms reproduce at a fairly rapid rate; though at 15 degrees 

 C. the fission rate was reduced approximately one halt. 



On Nov. 7 two temperature experiments were started, involv- 

 ing Clone X line x and line x-t, and clone Y lines y and y-/. The 

 same culture medium was used for both lines of a clone, and the 

 lines which were not kept in the low temperature incubator were 

 put in a darkened place to counteract any effect lack of light 

 might have had on the organisms in the refrigerator. As usual, 

 tests were made at frequent intervals to determine the interac- 

 tions of two diverging lines. The results obtained are shown 

 below by means of symbols. 1 In clone X reactions between 

 line x and line x-t on the 6th day + i + o, loth + i, I4th - 

 i i, i6th o o, I7th i - - , igth - - it. 



In clone Y reactions between line y and y-/ on the 6th day 

 + , 8th + + +, iolh -f -f, i2th + + +, I4th +'+ +, 

 i6th + o +, I7th o -, igih - -. 



+ signifies that fusion took place; - shattering reaction; o contact was made 

 but neither fusion nor shattering followed ; contact was not made. The number of 

 symbols placed after a figure indicates the number of observations made on that day. 



