392 



Profs. Percy Frankland and Marshall Ward. 



Stopped, because evidently abnormal. Doubling periods : 



1836 ft = 4.0 P.M. 4.45 P.M. = 45 minutes at 25 C. 



36 72 = 4.45 6.16 =91 25 25 -525-3* C. 



Normal doubling period* : 



31 -563 n = 4.30 P.M. 5.59 P.M. = 89 minutes at 2525 -525 -3 C. 



A very curious phenomenon occurred here. At 5.40 the filament 

 had ceased growing, and apparently measured only 49'5 ft whereas 

 it was 55 fi ten minutes previously. More carefnl observation showed 

 a length of empty sheath 9 /u long in addition, so that it was really 

 58'5 /n long, but the solid part had contracted itself. The cause of 

 this is not evident, and as the table shows, the temperature, &c., 

 could not have been responsible ; but the phenomenon is apparently 

 of the same order as the abnormality described on p. 356 by 

 exposure to intense insolation. At 5.45 the solid part was 54 fi long, 

 and at 5.50 it was 58'5 fi. By 6.5 the empty portion had partly 

 filled up again by a block separated by a piece of empty sheath 

 (about 1 fi long) from the main mass ; by 6.15 the abnormality 

 seemed quite repaired. 



I have no idea what could have induced this malformation : there 

 is an interesting question involving the maladies of a schizomycete 

 here, but I could only note it in passing. 



Its bearing on my present purpose is evident. The disturbance 

 caused the filament to take ninety-one minutes to double its length 

 against forty-five in the previous period ; evidently one cause 

 of this would be the loss of cell-divisions and their summation. 



* See p. 431 for explanation of the normal doubling period it is obtained by 

 dating the commencement of the measurements half an hour after starting the 

 growth, to allow the cell time to accommodate itself to the temperature. 



