456 



H. S. JENNINGS AND K. S. LASHLEY 



TABLE 50 



Experiment 15. Paramecium caudaium. Coefficients of correlation in numbers 

 of fissions for given periods, between the descendants of the members (a and b) 

 of pairs, and of split pairs, — in the case of conjugation between individuals of 

 the same pure race. 



The shorter periods are less significant, since fluctuations in 

 the environmental conditions produce in so short a time disturb- 

 ances affecting the coefficients. Yet they show essentially the 

 same relations as does the entire time; the positive coefficients for 

 the pairs are very high ; while for the split pairs there is no positive 

 correlation. 



The fact that we find for the first half of the experiment in the case of 

 the split pairs so great a negative coefficient as — 0.3175 naturally calls 

 for remark. The other coefficients for the split pairs are not greater 

 than might be expected in the absence of all correlation. But to what 

 is due this negative coefficient of — 0.3175? 



It can, I beheve, be affirmed positively that there was nothing in the 

 conditions of the experiment nor in the manner of keeping the records 

 that could give rise to any correlation, negative or positive, between the 

 two members a and h. They were kept in separate sets, handled separ- 

 ately, and their records were kept separately. With the great number 

 of experiments in progress, it was impossible for the experimenter to 

 have any idea as to whether a correlation was appearing or not; or con- 

 sciously or unconsciously to manipulate the records in such a way as to 

 tend toward either negative or positive correlation. Moreover the 

 facts to be entered in the record are so entirely clear as to leave no sphere 

 of action for unconscious personal bias. There remain then but two 

 conceivable explanations; the first is that there might be assortative 

 mating of such a character that a slowly reproducing specimen tends to 

 mate with a rapidly reproducing one, giving negative correlation. But 

 aside from the fact that there is no other evidence of this, and that it is 

 almost inconceivable how it could be brought about, (Ij it is known that 

 the members of the pure race are not differentiated before conjugation 



