140 



GENETICS 



in every horizontal line their number is more numerous 

 near the average for that line and less numerous at 



155 

 210 

 310 



FIG. 30. Diagram of the species Paramecium as made up of the 

 eight different races shown in Figure 28. Each horizontal 

 row represents a single race. The individual showing the 

 mean size in each race is indicated by a cross placed above it. 

 The mean for the entire lot is at the vertical line. The 

 magnification is about 24 diameters. After Jennings. 



the extremes, thus forming the typical normal fre- 

 quency curves of fluctuating variability. 



The significant fact about these series is that ex- 



