4 Mr. A. G. Levy. On the Elasticity of the Living 



FIG. 1. FIG 2. 



of the dial, rotates this in its excursions up and down. An index 

 hand attached to the axis indicates tenths of millimetres on the 

 dial. 



Below, the plunger has screw arrangements (h), by which discs 

 (i) of varying sizes can be applied. In all experiments a disc of 

 1 cm. diameter was used unless otherwise mentioned, and it was by 

 the screw attachment correctly adjusted to the surface of the brain. 

 The weight of the plunger was accurately counterbalanced by a 

 weight which acts over a pulley (j), so that the disc remains at rest 

 in any position, e.g., on the brain surface, without exerting any 

 pressure when there is no weight in the pan. 



This suspended counterbalancing weight also acted as a plumb 

 line by which the perpendicularity of the plunger was secured, this 

 position being essential to avoid all friction. The figures show 

 the apparatus applied to a horizontal surface. 



4. Method of Experiment. The animal, invariably a dog, was kept 

 under ether through the medium of a glass cannula, inserted into the 

 trachea and attached by india-rubber tubing to a funnel, this latter 

 being placed over cotton-wool saturated with ether. The narcosis 

 must be maintained equably throughout the experiment, to avoid 

 irregularity in respiratory movements. The head was firmly sup- 



