1879.] Mr Greenhill, On the rotation of a liquid ellipsoid. 233 



nerve with dilute acid, as well as weak stimulation of the cut 

 brachial nerve with bile caused a diminution in reflex time. If 

 this is true, it is rendered probable that there are impulses from 

 all portions of the skin surface travelling up the nerves to the 

 central nervous system, each impulse tending to make every nerve 

 centre more irritable, tending to make it discharge efferent im- 

 pulses more easily. Mr Langley, whilst rejecting the theory of 

 Setschenow of special inhibitory centres, considered that the 

 theory of Goltz and Freusberg required entire alteration as to the 

 mode in which inhibition of reflex action is brought about. 



If a frog without cerebral hemispheres be made to jump, in 

 jumping it shuts and opens its eyes, so if either fore or hind limbs 

 be stimulated just so much as to cause a single movement of the 

 limb concerned, the same reflex shutting and opening takes place. 

 If the skin of the fore part of the body be gently touched, the eye 

 is partially shut, sometimes the eye of the stimulated side only 

 without any other movement; in this case the eye is promptly 

 opened if a slight stimulus be applied to the skin of the hinder 

 part of the body, rarely when no movement of the limbs take 

 place. 



Again, if the animal is held and then turned over, the eyes more 

 or less completely close, and on turning back, open ; if moved at all 

 suddenly in any plane there is a shutting and opening of the eyes. 

 This diminishes, but is "lot prevented by section of all nerves from 

 the skin surface, or by section of the spinal cord up to second spinal 

 vertebra. The action is probably due to a disturbance of the 

 impressions starting from the semicircular canals. 



Some remarks were also made ur>on the croaking experiment of 

 Goltz and on the so-called cataplex^^'^.f frogs. 



March 24, 1879. 

 Professor G. D. Liveing, President, in the Chair. 



Mr H. M. Ward, Scholar of Christ's College, was ballotted for 

 and duly elected an Associate of the Society. 



The following communication was made to the Society: — • 



Mr A. G. Greenhill, M.A., On the rotation of a liquid ellipsoid 

 about its mean axis. 



Jacobi has shewn that an ellipsoid of three unequal axes is a 

 possible form of the free surface of a mass of liquid, rotating as if 

 rigid about one of the principal axes, and in this case the axis of 

 revolution must be the least axis. 



Mr Ferrers has shewn that the equations of equilibrium can be 



17—2 



