SIZE RELATIONSHIPS IX BLEPHARISMA UXDULAXS. IQ9 



this so well since they vary less than the non-conjugating popu- 

 lations. 



This brings us to the consideration of the second of the three 

 problems, i. e., the variation of conjugants and non-conjugants. 

 Table I. shows very clearly that the variation between the 

 extremes in the case of the conjugants is much less than that in 

 the case of the non-conjugants, being in the six lots: 



13.5 9.5 10.5 9.5 7 8.5 in the former, 



22 24 20 16.5 16.5 23.5 in the latter, 



the variation ranging from nearly two times to nearly three times 

 as great in the case of the non-conjugants. It is probable that 

 some of the shortest non-conjugants are ex-conjugants, which 

 would however not change the general results very appreciably. 

 Finally the third problem, as to coordination in size of the 

 members of the same pair, appears. By plotting a graph using 

 the length of the shorter of the two individuals as abscissa, and 

 the longer as ordinate, the number of pairs of each combination 

 which appeared was obtained. Then by adding diagonally, I 

 obtained the number of pairs in which the individuals varied 

 less than .5 mm. (or 2.2 microns, actual measurement), which 

 varied .5 mm., I mm., 1.5 mm., etc., the following table resulting: 



TABLE II. 



CORRELATION IN SIZE OF MEMBERS OF CONJUGATING PAIRS. 



Pairs. 



Both members equal in length 35 



One member shorter by 0.5 mm 57 



One member shorter by i.o mm 62 



One member shorter by i .5 mm 50 



One member shorter by 2.0 mm 34 



One member shorter by 2.5 mm 17 



One member shorter by 3.0 mm 9 



One member shorter by 3.5 mm 8 



One member shorter by 4.0 mm 2 



One member shorter by 4.5 mm 2 



One member shorter by 5.0 mm 2 



One member shorter by 5.5 mm i 



No two members of the same pair show a greater variation than 

 5.5 mm., though conjugating individuals of different pairs show 

 as great a variation as 14.5 mm.; and out of 279 pairs of con- 



