410 H. S. JENNINGS AND K. S. LASHLEY 



ANALYSIS OF OBSERVED RESULTS 



The view that there is a sexual differentiation between the 

 two members of pairs has been based upon two sets of facts: 

 (1) upon the distribution of survivals and deaths among the 

 ex-conjugants; (2) upon differences in the rate of fission between 

 the progeny of the two members of pairs. We shall deal with 

 these separately, taking up first the deaths. 



DISTRIBUTIONS OF SURVIVALS AND DEATHS AMONG THE MEMBERS 



OF PAIRS 



• Miss Cull's experiments 



We may analyze first the data given by Miss Cull ('07). 

 Ninety-three pairs of conjugants, giving 186 separate lines, were 

 isolated; each line was kept in a vial. At the end of seven days 

 32 of the lines had died out, including both members of pairs in 

 6 cases (that is, '6 entire pairs'). After twenty days 51 of the 

 lines had died out, including 13 pairs. After 30 days 83 lines 

 had died out, including 28 pairs. We have then three cases to 

 deal with. Is the number of complete pairs dead in any or all 

 of these cases less than would be expected if the distribution of 

 deaths had no relations to the pairing, as would be required if 

 this is to be considered evidence for sexual differentiation? Or, 

 what is the same thing, is the number of pairs surviving less than 

 would be expected if the distribution of deaths had no relation 

 to the pairing? We need to deal explicitly with but one of these 

 two questions, since the answer is absolutely identical in the two 

 cases. As a rule therefore we shall take up the question only in 

 the form first stated. 



First case. Here, after seven days 



m = 186 

 71 = 32 

 number of pairs dead = G 



Now, applying our formula (1) or (2), we find that the most 

 probable number of pairs, if the distribution of deaths is random, 

 is 2, although 3 is nearly as probable. The average number 



