452 Profs. Percy Frankland and Marshall Ward. 



The doubling periods (of entire curve) : 



24-75 49-5 p. = 2.30 V.M. 3.4 P.M. = 34 minutes at 30-7529 '5 30-25 C. 

 49-5 99-0,, = 3.4 ,,3.35 =31 30-25 31 C. 

 99 -0 198 -0 = 3.35 ,,4.13 =38 31 31 '75 C. 

 198 -0 396 -0 = 4.13 5.12 =62 31 '7532 -75 C. 



Calculated back : 



447 -75223 -75 /x = 4.22 P.M. 5.21 P.M. = 59 minutes at 31 '7532 '9 C. 

 112 -0 224 -0 = 3.40 4.22 =42 3131 '75 C. 



56-0112-0 ,, = 3.10 3.40 =30 30-25 31 C. 



28-0 56-0 ,, = 2.36 3.10 =34 29 -5 30-25 C. 



It is evident that even if we allow a wide margin for errors, 

 the curve and tables show that the period of breaking up of the fila- 

 ment coincides with a period of slowing of the growth, i.e., the high 

 temperature was beginning to tell on the growth, and the fourth 

 doubling period was nearly twice as long as the preceding ones. 



This accords very well with the experiment of November 7, where 

 the first doubling period was twenty-nine minutes, but that of a later 

 rod in the same culture was found to be over 120 minutes, fully 

 bearing out the conclusions there arrived at, namely, that the. tem- 

 perature begins to tell after a longer or shorter time. 



This culture had broken up into short separate segments of two to 

 five cells each at 10 P.M. (t. = 31'5), and on December 3 at 9 A.M., 

 had formed a few feeble spores here and there, while many empty 

 bits of sheath were seen. The sister culture kept at 22 all the time 

 was now a fine normal crop of long-coiled tresses, and must have 

 measured several thousand times the lengths of the starved-looking 

 crop above described. Nevertheless, the drop of gelatine in the 22 C. 

 culture was certainly no bigger than that at the higher temperature, 

 but, if anything, a little smaller. These cultures alone were sufficient 

 to convince me that it is not a question of quantity of food-materials 

 originally given. 



On November 5 spores were sown at 9 A.M. in 10 per cent, normal 

 gelatine, and kept at 22 C. until 3.10, when the germinated fila- 

 ments were put into the Sachs' box, which stood at 35 C. 



A filament was selected measuring 40'5 ft with the following 

 results. It must be remembered that this first series of measure- 

 ments was made during the period of accommodation to the high 

 temperature, and while the box necessarily opened for arrangement 

 was recovering from the consequent lowering of the temperature. 

 Variations of temperature are much more difficult to control as they 

 get higher. 



The filaments in this normal gelatine show their septa much more 

 sharply than in broth, and, as we see, grow fairly rapidly at these 

 temperatures. 



The curve shows that the doubling period here was : 



