148 Miscellaneous. 



dead contractile fibrilla rolled up like a tendril, persisting in this 

 state of contraction, and having lost for ever the faculty of elonga- 

 tion. 



I have several times observed that as soon as the body of a Vorti- 

 cella detaches itself from the stalk to which it normally adheres, the 

 contractile stem begins to execute a series of movements of rotation 

 round the axis. Each of these movements is accompanied by the 

 formation of a spiral turn ; and when the whole of the stalk is thus 

 converted into a close spiral, the movement ceases, and no elongation 

 afterwards takes place. 



The elongation of the spiral fibrilla, the organ of muscular move- 

 ment in the Vorticellce, is therefore dependent on the state of life — 

 that is to say, on the continuity of nutrition and the exchange of 

 materials. From the moment when nutrition is suppressed by the 

 death of the animal, or by the separation of the fibrilla from the 

 nutritive centre, the contractile element takes and retains the 

 natural form inherent in its structure — that of a spiral spring, of 

 which the turns are at the maximum of approximation in the state 

 of repose. 



The contraction of the muscular fibre of the stalk of the Vorti- 

 eella corresponds with the state of repose of the spring ; it is the 

 immediate consequence of its elasticity ; the elongation of the fibre 

 is the result of the forced extension of the spring by a cause of 

 movement dependent on the act of nutrition, and acting during the 

 apparent repose of the contractile organ. As soon as the source of 

 this antagonistic force is exhausted, elasticity, recalling the muscle 

 to its natural form, produces the so-called movement of contrac- 

 tion. 



Is this a phenomenon peculiar to a singular organ of locomotion, 

 the stalk of the Vorticella ? or is it the condition of muscular con- 

 traction in all animals? 



I shall hav€ the honour very shortly to communicate to the Aca- 

 demy the results of numerous experiments which I have undertaken 

 upon muscular contraction in the higher animals, their results 

 establishing : — 



1 . That a recent hypothesis, according to which permanent con- 

 traction is essentially constituted by a series of successive shocks or 

 vibrations, is in absolute contradiction to well-observed facts. 



2. That a tendency towards extreme contraction is a property 

 inherent in living muscular fibre, a necessary consequence of its 

 structure and elasticity. 



3. That during life this tendency to contraction is combated by 

 a cause of extension which predominates during the repose of the 

 muscle, is developed in the exchange of nutritive materials, increases 

 with the activity of their access, diminishes or becomes extinguished 

 by their exhaustion, and may be momentarily suspended by all the 

 excitants of muscular contractility — nervous action, heat, the electric 

 shock, &c. — Comptes Rendus, June 3, 1867, pp. 1128-1132. 



