90 



MORPHOLOGIC VARIATION 



Chapter III. They illustrate well the increase in size during the 

 period of active growth. After growth has come to a standstill and 

 the cells have returned to their original size, subsequent variations 

 are slight and probably of no significance. 



This negative correlation between the length and area-length 

 index of the cells will be perhaps more apparent by an inspection 

 of Figure 25, in which every tenth cell in the array of 200 from 

 each sample has been superimposed in a column upon the growth 



3 hrs. 



CECCJ 



6 hrs. 30 hrs. 



T — T — r 



9 hrs. 96 hrs. 



Frenuency Distributions: Length of Cells. 

 Abscissas: 1 unit=lu. Ordinates: 1 unlt=2^ 



Fig. 



26. Frequency Distributions of Cells According to Length and 

 Area-length Index. B. coli. 



curve plotted logarithmically with regard to time, as well as to the 

 number of cells. (Since cell counts were made only every three 

 hours, this curve has been drawn in a rather free-hand fashion, 

 but is probably fairly close to the true growth curve.) Again the 

 marked increase in size during the period of active growth is appar- 

 ent. The columns of cells have been arranged in the order of their 

 area-length index, not in the order of their length, but it will be 

 seen that as a matter of fact this method does roughly classify 

 them according to their size. The longest cells in each column are 



