966 



Catalogue, several groups of nebulse have been discovered, in some 

 of which nebulous connexion has been detected between individuals 

 of the group, in others not. Sketches of some have been made and 

 measures taken ; but although the subject of grouped or knotted 

 nebulas is considered one of deep interest, it has not yet been pro- 

 ceeded with far enough to warrant entering upon it in the present 

 paper. 



The conclusion of the paper is occupied with remarks relating to 

 each figure, in order to render the information conveyed by it more 

 complete, and these are stated to be for the most part extracts 

 selected from the Journal of Observations. 



2. " Electro-Physiological Researches. — Ninth Series." By Signor 

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



In the first portion of this paper the author refers to a work re- 

 cently published by M. Du Bois Raymond " On the law of Muscular 

 Current, and on the modification which that law undergoes by the 

 eff'ect of Contraction ;" which work M. Matteucci states obliges him 

 to transmit to the Royal Society certain researches the publication 

 of which he would otherwise have wished to delay. He then refers 

 to his previous researches published in the Philosophical Transactions 

 for the years 184-5 and 1847, and in the Annales de Chimie for 

 October 1847. From the experiments detailed in those papers, and 

 from certain points of doubt which he indicates, he considers him- 

 self authorized in concluding that the development of electricity by 

 muscular contraction still remains to be demonstrated by experiment, 

 and that the phenomenon of induced contraction is still that which 

 leads most directly to this result. 



He then gives a series of experiments illustrated by figures, and 

 from them deduces the following conclusions : — 



1st. The cause of induced contraction, according to all analogies, 

 is the same as that which produces contraction of the galvanoscopic 

 frog in several of the experiments given. 



2ndly. The cause of these contractions is evidently an electrical 

 phenomenon developed in the act of contraction, and which consists 

 in a diff'erent state of electricity in the different points of the con- 

 tracted limb. 



Srdly. This electrical phenomenon, like the contraction which 

 produces it, lasts only for an instant. 



^thly. These electric states, developed by contraction, tend to 

 produce electrical currents which circulate in opposite directions 

 across a conducting arch interposed between the two limbs, which 

 contract at the same time. 



The author further states, that, whatever the theory of these phe- 

 nomena may be, it is certain that they demonstrate the production 

 of an electrical disequilibrium in the act of muscular contraction. 

 Upon the question whether the cause of the species of discharge de- 

 scribed is a phenomenon analogous to that of electrical fish, or a 

 change in the natural conditions of the muscular current, the author, 

 though leaning to the former alternative, forbears to express a posi- 



