1865.] Movements in Cells. 231 



Our view regarding the nature of the force which produces such mar- 

 vellous phenomena as those known to result from nervous action, will be 

 materially influenced by the conclusion which we are led to accept regarding 

 the fundamental arrangement of the nerve-cells and fibres, central and 

 peripheral. 



If it could be shown that a nerve passes from its centre and ends by free 

 terminations, or by becoming continuous with the muscular tissue, we should 

 scarcely adopt the same general conclusion regarding the manner in which 

 the nerve-centre influences the contractile tissue as we should if it were 

 shown that the nerve merely passed amongst the muscular fibres without 

 being necessarily even in actual contact with them, and returned towards, 

 and eventually became connected with, the nerve-centre, without there being 

 any solution of continuity in any part of the circuit. The investigations re- 

 corded in this and other memoirs have led me to conclude th#t nerves 

 invariably form circuits, and that there are in truth no ends at all. I 

 believe that the nerve machinery is a complete circuit, and that the active 

 phenomena are due rather to an alteration in the intensity of the current 

 passing along the nerves, than to its sudden interruption and completion. 



In this Lecture I hope to be able to adduce facts which indicate the 

 existence of fibres passing from and towards all central and peripheral 

 nerve-cells. 



Before I proceed to the special subject of my Lecture, I must offer a few 

 remarks upon contractility. Of late this term has been applied to move- 

 ments occurring in living organisms which seem to me to be quite distinct 

 in their essential nature from contractility. I cannot hold that the move- 

 ments occurring in an amoeba or white blood-corpus.cle are of the same 

 nature as those which occur in muscle, and I cannot, therefore, regard both 

 classes of movements as manifestations of one property, contractility. 



Of THE MOVEMENTS OCCTTEKIXG IN CELLS AND IN THE TISSUES OF LlVING 



BEINGS, AND ON CONTKACTILITY. 



Vital movements. The peculiar movements occurring in a mass of ger- 

 minal matter are illustrated by the drawing now exhibited. Protrusions 

 may occur at one or many points of the mass at the same time, and the 

 whole mass may move in one direction like an amccba. Now it will scarcely 

 be maintained by any one that the changes of form occurring in a mass of 

 living matter are due to external agency. As far as can be ascertained by 

 observation, the movement is primary, and depends upon the active forces 

 inherent in the matter itself. This form of motion has never been explained 

 or accounted for ; but as it ceases with the death of living matter, it is 

 only reasonable to infer that it is intimately associated with those other 

 phenomena which are peculiar to matter in the living state. It may 

 therefore be termed vital motion, to distinguish it from every other kind of 

 movement known. The rotation and other movements affecting the " pro- 



