BIPARENTAL INHERITANCE IN PARAMECIUM 



441 



that any irregularities in the experimental treatment would tend 

 to decrease any correlation that might intrinsically exist. Yet in 

 every period there is a marked coefficient of correlation, which as 

 a rule is ten to twenty times as great as its probable error. 



The effect of possible similarity in conditions in the case of 

 strains lying adjacent to each other in the culture chambers was 

 tested in the following way : In the present experiment, where 

 the a's formed one series, the 6's another, the two lines la and 2a 

 occupy the two concavities of a single slide; the lines 3a and 4a 

 the next slide, and so on. Hence the a of a given odd numbered 

 pair, and the a of the succeeding even numbered pair are through- 

 out immediately adjacent, and therefore under similar conditions. 

 The same relations hold for the 6's. If therefore, this similarity 

 of conditions due to adjacence in the experiment has any effect 

 in producing correlation, as suggested on page 434, then this 

 should give a positive coefficient of correlation when we compare 

 the odd numbered line with its following even numbered line. 



TABLE 45 



Experiment 16. Paramecium caudatum. Coefficients of correlation between the 

 number of fissions for a and that for b (a and b being the two members of a pair), 

 for the various periods embraced in table 51. In each case, save where the word 

 'all' is appended, the coefficient is based on the fissions of pairs of which both 

 members lived through the period in question. Where the word 'all' is appended, 

 the actual number of fissions for the entire 241 pairs is dealt ivith, including those 

 that died out before the end of the period in question. 



COEFFICIENT OF 

 CORRELATION 



First 10 days 



First 10 days, all 



First 10 days, omitting those that did not 



divide 



Second 10 days 



Third 10 days 



Third 10 days, omitting those that did 



not divide 



Fourth 10 days 



First 20 days 



Second 20 days 



Total 40 days 



Total 40 days, all 



0.3068 ± 0.0311 

 0.3770 ± 0.0264 



0.3319 ± 0.0314 

 0.3862 ± 0.0305 

 0.2690 ± 0.0334 



0.3038 ± 0.0328 

 0.1021 ± 0.0365 

 0.4793 =fc 0.0275 

 0.2094 ± 0.0354 

 0.3450 ± 0.0326 

 0.3842 ± 0.0263 



