246 A Biometncal Study of Conjugation in Paramecium 
Series A. 
160 
150 
130 
180 170 
Length. 
Diagram IV. Showing the relation of the index-length correlations for conjugants of series A. AB is the 
regression line of index on length when all correlation between length and breadth in the individual 
is destroyed. It is the regression line for the spurious correlation between index and length 
A'B' is the "gross" or observed line of regression of index on length. The shaded portion shows 
the area through which the " spurious" line is moved (in the direction of the arrows) as a result of 
the existence of an organic correlation between length and breadth in the individual. 
Series A. 
250 240 230 220 210 200 190 180 170 160 150 140 
Length. 
Diagram V. Showing the relation of the index-length correlations in the non-conjugants of Series A. 
The significance of the letters is the same as in Diagram IV. 
