A Study in Variation. 61 
which the specimens vary : these curves have the following 
formulae : 
Maximum curve. .oi35h 2 -f 1.169I1 — .044 
Minimum curve .105I1 2 + 1.28311+ .013 
It is seen from these curves that the variation increases in 
amount as the specimens increase in size : that is, as they 
approach maturity. Compared with the latitude in other 
factors^ the variation in this instance is small, most of the 
specimens lying within a range of 20 per cent., about half the 
'•5 75 1 . 25 S 75 z zs 5 75 3 zs S 7 S 
Fig 6. Illustrating the maximum and minimum curves in the variation of 
height to breadth. 
jf 
range in the other factors. This indicates that the ratio of 
height to breadth remains almost constant during growth. 
In the diagram representing x 100 Fig. 3 B, 
it is seen that the range is considerable, 53 per cent. The 
mean of the factor is 70.33, indicating that a similar ratio 
occurs here as in X 100 although the range is 
considerably more. 
The arithmetic mean deviation is 8-76 or 12-31 per cent, 
of the mean for the species. The largest number of specimens 
is seen to lie within narrow limits 60 per cent — 80 per cent, 
and represents the mature individuals, while those outside 
these limits, represent either very young forms when the 
relation is low, or very large specimens when the relation 
approaches 100 per cent, and the specimens present a quadrate 
appearance. 
(To be continued.) 
1933 March 1 
