THE END.

FOOTNOTES:

[1] Darwin, Descent of Man (2nd ed.), p. 159, note 23.

[2] The power of magnification of a lens is the ratio of its focal distance to 10 inches. Thus a lens of 1 inch focus (or focal distance) magnifies 10 times (written × 10, or ten diameters); one of ½ in. focal distance, 20 times, and so on.

[3] A Popular Handbook to the Microscope, p. 39.