Manchester Memoirs, Vol. lix. (191 5), No. 4. 13 



Since the concentration is along the line a a! we 



see that there is some degree of direct correlation ; i.e., 



when the value of -jz is low, the value of 73 tends to be 



low, and vice versa. We see further that the value of this 



„ „ . , . , , . . , Length .. Length 



Fif. 7. — Graph showing the relation or the - — =-— - and — — 2— 



61 h s Breadth Depth 



ratios among 1000 individuals of Retiatlaria lineata (reduced 



from Fig. 5, q.v.). 



L 







D 









b 



a 



above 









198-46 



232'77 



1-525 









144 



287 



X 



below 









262 6 



308-09 



*'5 2 5 









3085 



2455 



below -875 



above "875 



L 



15 



correlation is '21, when complete correlation would be 

 represented by unity. In other words, this may be 

 expressed by saying that of the whole variation one-fifth 

 is strictly correlated and four-fifths are un correlated. 



