6 Charles Zeleny. 



parts limited only by the extent to which the rigidity of the skeletal structures may 

 counteract such a tendency. We may in this manner get at the forces which are 

 active in correlation at the time of and subsequent to the operation. The main 

 difficulty with the method must consist in the reaction to the stimulus of the injury 

 itself, a factor which does not enter into the normal relations of the parts. 



A sample result will illustrate the method in a more concrete 

 manner. When an asymmetrically placed leaflet of a five-leaved 

 form (white lupine or Virginia Creeper) is removed at the earliest 

 possible stage, the remaining four leaflets take up positions 



C 



Fig. I. 

 Virginia Creeper, Parthenocissus quinquefolia. Diagram of changes in position and length of leaflets 

 of compound leaf after removal of one of their number ( X §)• Unbroken lines — Original positions. 

 Dotted lines — Resultant positions. Barred lines — Removed leaflet. P — Petiole. Arrow — Direction 

 of movement. A, B, C, D, E — Original positions. Ai, B\, C\, E\ — Resultant positions. 



which tend to approach those of the units of a symmetrical 

 /owr-leaved system, the chief change of position being confined to 

 the two leaflets which were asymmetrically placed after the opera- 

 tion. In the case of the Virginia Creeper the resultant change 

 of position was +5°.9 for leaflet A, +I2°.2 for leaflet B, +24°. 4 

 for leaflet C, and —3°. 2 for leaflet E. (See Fig. i.) Likewise in 

 a three-leaved system (the red clover) after removal of an asym- 



