Size in Relation to Multiplication Rate 91 



When, however, four sister progeny from a single 

 parent, growing in a single dish of culture medium, 

 were compared with respect to age and to size attained, 

 then there was a small but significant correlation 

 (table 7). The individuals which lived longest were 

 those that grew to the largest size. This held true 

 in two clones which were very different in absolute 

 sizes; and the correlation coefficient of +0.271 was ap- 

 parently of a significant value. 



The interpretation of this plain result is slightly 

 involved. If the small individuals had been those 

 which divided later, then evidently they had delayed 

 in order partially to come up to a standard size. If 

 the small individuals divided first, then size would be 

 regarded as having practically no influence upon the 

 initiation of fission. As it actually turned out that size 

 and age were positively correlated, it is just to conclude 

 that the normal variation of duration of life was not 

 influenced by the size of the individuals. When the 

 processes which have to do with age came to a certain 

 point, fission occurred regardless of how much body 

 substance was present. 



As a result, the older individuals accumulated 

 slightly more body substance for the reason that 

 they had more time in which to acquire body sub- 

 stance. 



It must be stated, however, that the age of maturity 

 is not independent of size when environmental factors 

 come in to retard the growth of individuals. When 

 increase of body size was inhibited through lack of 

 food, it turned out that partially starved individuals 

 delayed their reproduction by several hours (figure 

 41, later on). Within the extra time they were able to 

 make up the deficiency of size in small part; but ulti- 

 mately they divided at sizes significantly smaller than 

 those which were adequately fed. 



