428 Profs. Percy Frankland and Marshall Ward. 



Doubling period : 



31 -563 /x = 3.1 P.M. 3.40 P.M. = 39 minutes at 28 -52928 -8 C. 



Or calculated back : 



67 -533 '75 /j. = 3.5 P.M. 3.50 P.M. = 45 minutes at 28 '7529- 28 '6 C. 



Segment B. 



The growth had ceased (as said under segment A). 

 Doubling period : 



90180 n = 3.1 P.M. 3.45 P.M. = 44 minutes at 28 '52928 '7 0. 



Or calculated back : 



18994 -5 fi = 3.3 P.M. 3.50 P.M. = 47 minutes at 28 '52928 '7 C. 



If we now summarise all these results, it is seen that there are 

 three points to be considered as regards the growth and behaviour of 

 the organism, (1) The rate of germination : (2) the rapidity of post- 

 germinal growth, or, what is here the same thing, doubling period, 

 and (3) the time occupied in completing the life-cycle from spore to 

 spore. The labour involved in making out all these points accurately 

 would be enormous, and I have only been able to concentrate my 

 attention on the growth curves, and to go accurately into the doub- 

 ling periods ; though, as we see, some interesting data are given con- 

 cerning the other phenomena, wherever they could be noted. 



Secondly, it will be seen that while paying especial attention to the 

 one point the influence of temperature on the doubling period I 

 had occasion to test to some extent the effects of altering the medium 

 in which the growth occurs, and the results are sufficient to show 

 that here, again, there is a large and interesting field for enquiry. 



Thirdly, the question arose as to whether any difference is 

 observable between the behaviour of filaments, grown direct from the 

 spore, in a given medium at a given temperature, and those grown 

 from a segment of greater age ; and although here again the enormous 



