414. MR. K. PEARSON ON THE MATHEMATICAL THEORY OF EVOLUTION. 
On the other hand, there are, I think, some points of first-class theoretical impor- 
tance in the mode adopted by Dr. Tuiste for expressing frequency ; it gives us a 
means of expanding all varieties of frequency curves in a series of factorial functions 
which may Jead to important theorems in the analysis of heterogeneous material. | 
PLATES. 
The scale of the accompanying figures is not that of the original drawings, and the 
clearness and distinctness of the several curves of the same figure have heen, in 
several instances, partially lost by the process of reproduction and reduction. In 
every case the square element of the figure corresponds to the square centimetre of 
the original diagram, and is spoken of both in the text of the memoir and on the 
figures themselves as a square centimetre. The scale of actual reduction is indicated 
by a fraction placed at the lower right-hand corner of the figure. 
