DAVENPORT AND BULLARD. — CORRELATED VARIATION. 



89 



In the following table, which is based upon the preceding, the num- 

 bers are all reduced to per milles. The two lines of totals are here, 

 accordingl}', replaced by means. A glance at this table shows a close 

 parallelism between the distribution of glands in the four cases. 



TABLE IL 

 Summary per Mille. 



Several interesting questions now arise : 



(1) How closely similar is the average number of glands in the two 

 sexes, and in the right and left leg of the same sex ? 



(2) "Which sex shows the greater variability, and to what extent is it 

 greater? Is the relation between the variability of the right and left legs 

 closer than that between the two sexes ? 



(3) How closely correlated are the numbers of glands on the right 

 and left legs of individuals ? That is to say, what are the chances that 

 a swine which has 2, 4, or 7 glands on the right leg will have the same 

 number on the left leg also? 



1. J7ie Relation between the Abundance of Glands and the Sex or the 



Side of the Body. 



The average number of glands on a leg of either sex is determined by 

 dividing the total number of glands counted in that leg by the number of 

 individuals of that sex, in this investigation 2,000. This gives us the 

 following result : — 



