185 
be made durer the proneness or not of the Vadis 
aborigines to vary individual as compared with 
mixed or less purely bred races. Prof. Pearson and bint Kol 
leagues in the Philosophical bra jin of the Royal So- 
ciety, London, have, duri the t few years, published 
Contributions to t Modal Theory of Evolu- 
tion, showing how variatio y be ibited by mathemati- 
economic, and biolo ical investigations, as, for instance, 
various types of anthropological measurements. They say, 
“if measurements be made of the part or organ in several 
the sıze of the organ, an y the number of 
specimens falling within a Mio des. range, d x of or; 
is curve may be termed a frequency curve e centre or 
gin for measurement of the organ may be taken as th 
mean of all the specimens m red. t cases, as in the 
case of errors of observation, they have a fairly definite symme- 
trical shape, and one that Presta sf with a close degree of ap- 
proximation the well known or probabi lity curve. 
A. frequency-curve, h for EMG 
presented by the error-curve, will termed a vole nii 
en a series of measurements give rise to a normal-curve, 
may probably assume so approaching a stable 
ti partially 
round the mean. In the case of certain biotogiesl sociologi- 
cal, and economic measurements there is, however, a well- 
marked deviation from the normal shape, and it becomes im- 
porno determine the direction and amount of such devia- 
more data and the greater the numbe in- 
Th n 
dissi observations there are, the more correct would be 
any such comparative measurements, and we may confidently 
expect that the projected extended anthropological investiga- 
tions of Prof. Spencer and Mr. Gillen will add greatly to the 
already accumulated store. The pr vomp on is that such 
an enquiry would show SM ped curve would approach more 
nearly a normal-curve so a type as the Austr. 
abortos than in > more d European races. — 
