1888.J Muscular Movements in Man and their Evolution, 



329 



II. " Muscular Movements in Man, and their Evolution in the 

 Infant : a Study of Movement in Man, and its Evolution, 

 together with Inferences as to the Properties of Nerve- 

 centres and then- Modes of Action in expressing Thought." 

 By Francis Warner, M.D., F.R.C.P., Physician to the 

 London Hospital and Lecturer on Botany in the London 

 Hospital Medical College. Communicated by Professor J. 

 Hutchinson, F.R.S. Received June 12, 1888. 



(Abstract.) 



Movements as signs of brain action have long been studied by the 

 physiologist ; but before proceeding to give an account of the visible 

 evolution of voluntary movement in man, it is necessary to define the 

 different classes of movements seen, indicating the criteria by which 

 the observer may be guided in the examples before him. Movements 

 may be classed according to the parts moving, the time, and the 

 quantity of each movement. These are the only intrinsic attributes 

 of such acts. If the nerve-centres which send stimuli to the muscles 

 are acting in equilibrio, the static outcome is seen in the postures 

 resulting in the body ; hence postures are signs of the ratios of action 

 in the nerve-centres, and indicate their present state or mode of 

 action. Typical postures and movements are described. A variation 

 in the ratios of action in the centres leads to visible movement. 

 Certain postures and movements are found by experience to corre- 

 spond to certain recognised brain states. Movements may occur in 

 combinations and in series ; special combinations and series of move- 

 ments determine the outcome of the action of which they are com- 

 ponent parts. It is shown that the time of action in the various 

 centres thus determines the outcome of the action, and is itself con- 

 trolled by impressions received through the senses. When movements 

 are seen, not controlled by present circumstances, they are probably 

 the result of antecedent or inherited impressions ; such are called 

 spontaneous. 



Section II. Evolution of Movements in Man. 



The new-born infant presents constant movement in all its parts 

 while it is awake, and this is not controlled by impressions from 

 without. Graphic tracings of such movements are given. This 

 spontaneous movement in the infant appears to be of great physio- 

 logical importance, and is here termed " microkinesis." It is argued 

 that the mode of brain action which produces microkinesis is analogous 

 to the action producing spontaneous movements in all young animals, 

 and to the modes of cell-growth which produce circumnutation in 



