The Experimental Method                    11

hard to draw, and since I shall not hesitate at times to enter
upon the physiological side of many problems, I have chosen
the somewhat broader title of Experimental Zoology to include
the subjects to be treated.

The principal topics to be discussed fall under the following
six headings: —

I. Experimental Study of Evolution.
II. Experimental Study of Growth.

III.   Experimental Studies in Grafting.

IV.   Experimental Studies of the Influence of the Environ¬

ment on the Life-cycle.
V. Experimental Study of the Determination of Sex.
VI. Experimental Study of the Secondary Sexual Characters.