Karl Pearson 407 
Let us next investigate how the volume of the corpuscle changes with increasing 
body length. A rough measure of this volume may be taken as y = hH, where b is 
the breadth and I the length of the corpuscle. If L etiual the body length then 
very closely : 
^Vonz + ViTiL 
VyL — —, ^ . 
^ 4tVb' + vf + 4!VbVini 
Now the constants of the breadth frequency are 
Mean = -01530 mm. Standard Deviation = -00208 mm. 
Coefficient of Variation = = 13'575. 
Hence remembering that Vi = ll-Qd, ?-ii= --016, ?u= -'245 and rM = -30G, we 
deduce : 
r,i=--101. 
We therefore conclude that the corpuscular volume decreases very slightly with 
the growth of the tadpole, but the more significant change is the negative cor- 
relation of corpuscular length, or the reduction of the corpuscular length with 
growth. 
For comparison we have only the relatively few toadpolls, whose corpuscles 
were measured by Dr Warren. These give us the results below : 
TABLE IV. 
Comparison of Breadth in Corpuscles from Tadpoles of Toad and Frog. 
Number 
Mean 
Standard 
Deviation 
hi 
hh 
'•/X 
B. vulgaris ... 
R. temporaria. . . 
725 
1775 
-01581 
•01530 
•00186 
-00208 
11-74 
13-58 
-520 
-306 
- -196 
- -016 
-•277 
-•245 
It will be noted that the breadth is a more variable character than the length 
of the corpuscle in tadpoles. For toadpolls the variation is almost equal for length 
and breadth, but all the correlations are higher. In particular = — -252, being 
more than double the tadpole value. The smallness of the sample does not allow 
of our placing much stress on these differences, but in the essential featui-e that the 
blood corpuscle becomes smaller as the organism develops the toadpoll confirms the 
tadpole results completely. 
For our present purposes it is desirable to follow out further the effect of 
increasing length on the breadth of the tadpole corpuscle. The value of the 
correlation ratio, t), was calculated from the length-breadth table (Table E, p. 416), 
and we found that while : 
r = -306 ± -015, 
7? = -350. 
