144 Regulation of Size in Unicellular Organisms 



(figure 46). Obviously the size was largest when mul- 

 tiplication was most rapid. In finer analysis, Henrici 

 ('28, p. 70) showed that the maximum size was reached 



1 2 3 4 S 6 



Age of culture in hours 



8 



Figure 48. Progression of body length in Bacillus megatherium in rela- 

 tion to the concentration of nutrients. Agar media with varying concentra- 

 tions of peptone and beef extract were compared, the strongest concentration 

 being 16 times the weakest. Concentrations 1 and 2 were not shown, but the 

 progressions were very similar to that for concentration 4. (Redrawn from 

 Henrici, '24b). 



exactly when the maximum rate of multiplication was 

 reached, both diminishing thereafter. The enlarge- 

 ment of the body did not take the place of multiplica- 



