86 MORPHOLOGIC VARIATION 



once more, the cells in the new culture again showed a lag before 

 they commenced to increase, and reached practically the same maxi- 

 mum as in the parent culture, the curve having practically the same 

 form as that of the culture from which the seeding was taken. 



Here, then, is further evidence that the size of the cells is cor- 

 related with the rate of growth. When a culture is transplanted 

 at a period during which the cells are increasing in size, they continue 

 to increase in size in the new medium; just as Chesney found when 

 a culture is transplanted during a period of maximum growth rate, 

 it continues to grow at a maximum growth rate in the new medium. 

 When the cells are transplanted during the period of decreasing 

 size, they immediately recover and increase again in the new medium, 

 but if transplanted at the time when they had reached their minimum 

 size, corresponding with the resting period or period of no growth, 

 they show a lag in the new medium, just as Chesney found there 

 was a lag in the curve for rate of growth. 



Frequency distribution curves of these cultures also support the 

 previous observation that the degree of variation in cell size is cor- 

 related with the actual size attained, that is with the actual rate 

 of growth in the culture. The parent culture showed the extension 

 of the base line, and flattening of the peak during the period of 

 maximum cell size, as was observed in the previous cultures. In 

 the two-and four-hour subcultures, this extension and flattening was 

 increasingly greater, but in the eight-hour subculture the frequency 

 curves were practically identical with those in the parent culture. 



