478 LORANDE LOSS WOODRUFF AND RH. ERDMANN 



one division against three divisions, whereas a more true, but 

 not a perfect, picture of the state of affairs is given by the state- 

 ment that four divisions occurred in forty-eight hours. One 

 might follow this argument to its logical conclusion and assmne 

 that the best method of presentation would be to average for 

 considerable periods, e.g., 10 or 30 days, but this obviously would 

 tend to obliterate any fluctuations in the rate which are not of 

 relatively long duration. The adoption of the five-day period 

 was made in recognition of both of these contingencies, and it 

 was of a duration particularly well suited to show the effect of 

 the process on the reproductive rate, because the process extends 

 over about nine cell divisions or a period of about six days. 

 Consequently the effect of the process makes itself evident in 

 the five-day plot. Certain apparent irregularities in the coin- 

 cidence of the phenomena are, from an actual study of all the 

 data at hand, clearly due to the fact that the five-day period is 

 not ideal. 



In a consideration of the relation of rhythms to the reorgani- 

 zation process it will be convenient to consider first the data 

 from Line VI, Subculture IE, since animals from this line were 

 preserved every day of its existence and, during the process, 

 every animal was preserved except the one needed to keep the 

 line alive. 



Inspection of the graph of this line shows at a glance five 

 fluctuations in the reproduction rate which would naturally be 

 interpreted as rhythms (cf. text fig. 16) while a study of the 

 cytological condition of the specimens shows that the low point 

 of each of the first four fluctuations is coincident with the pro- 

 found nuclear changes of the reorganization process. The fifth 

 fluctuation, during which the division rate fell to nearly three- 

 quarters of a division per day, was brought about by the con- 

 tamination of the medium at the time of transference with a 

 deleterious strain of bacteria, from the effects of which the ani- 

 mals of this line never completely recuperated and succumbed 

 upon the recurrence of the process for the fifth time. Conse- 

 quently it is evident that four out of the five fluctuations are 



