^6i Royal Society. 



the deflexion fringes decrease, and the inflexion fringes increase with 

 the distance from the direct rays. 



Proposition VIII. 



The joint action of two bodies situated similarly with respect to 

 the rays which pass between them so near as to be affected by both 

 bodies, must, whatever be the law of their action, provided it be in- 

 versely as some power of the distance, produce fringes or images 

 which increase with the distance from the direct rays. 



Proposition IX. 



It is proved by experiment that the fringes or images increase as 

 the distance increases from the direct rays. 



These propositions are illustrated by particular instances, and their 

 truth is shown by experiments and by some mathematical investiga- 

 tions. The author concludes his paper by a ^ew observations tending 

 further to illustrate and confirm the foregoing propositions, and for 

 the purpose of removing one or two difficulties which had occurred 

 to others until they were met by facts, and also of showing the 

 tendency of the results at which he had arrived. 



2. " Electro-Physiological Researches." — 7th Series. By Signet 

 C. Matteucci. Communicated by W. R. Grove, Esq., F.R.S, 



In this memoir, Prof. Matteucci, after recapitulating the results of 

 his previous researches on electro-physiology, published in the Philo- 

 sophical Transactions, proceeds to the relation of new experiments. 

 He first shows that nervous filaments made to conduct an electric 

 current in a liquid are not capable, like metallic wires, of acting as 

 electroids, and giving rise to electro-chemical decomposition. The 

 solution employed was that of iodide of potassium ; the nerves, two 

 large ones Jaken from a living animal, each of which was separately 

 attached to the metallic extremities of a pile of fifteen couples. No 

 trace of decomposition followed ; and he concludes from hence, that 

 the conductibility of nervous matter is due to the liquid part of the 

 matter itself. 



He then gives further experiments on the relative conductibility 

 of muscles and nerves, with a view to ascertain whether, when a 

 current was impelled through a mass of muscle, any part of the cur- 

 rent might have passed through the nervous filaments spread through 

 that muscle. For this purpose he inserted the nerve of a galvano- 

 scopic frog into a hole made in a piece of dead muscle, through which 

 he then passed a very powerful current : no contraction followed 

 in the galvanoscopic frog. When muscles still retaining their irri- 

 tability were substituted for the dead muscle, induced contractions 

 occurred in the galvanoscopic frog during the passage of the current. 

 He concludes that when the poles of a pile of twenty-five or thirty 

 elements are applied to the surface of the muscles of a living animal, 

 the phenomena produced by the passage of the current must depend 

 either on the direct action of the current on the muscular fibre, or 

 on the indirect a.ciion or influence of the electric current transmitted 



