484 



G. N. CALKINS AND L. H. GREGORY 



TABLE 3 



Mean lengths in microns of 16 pure lines from ex-conjugant J, arranged 



in groups 



may indicate a correlation between stability and conjugating 

 power. 



The same correlation is shown by the coefficients of variation 

 for the two measurements in respect to proportions of length to 

 breadth given in table 4. 



6. VARIATIONS IN CONJUGATING POWER OF PURE LINES 



We now come to the most interesting and suggestive results of 

 these experiments, namely, the differences shown by different pure 

 lines from the same ancestral ex-conjugant in respect to the abil- 

 ity to conjugate. The methods employed in the conjugation tests 

 have been described (p. 471) but attention may be called again 

 to the fact that conjugations do not occur in the permanent cul- 

 tures and that conjugations unless otherwise stated, are always 

 strictly paedogamous. 



