natural) in respiration. For the lungs, like the heart, are continually carried upwards and downwards by a natural (i.c., unconscious and involuntary) movement, and are excited by any irritation to coughing and more frequent action; but they cannot form and regulate the voice, nor can singing be executed, without the assistance and in some sort command, of the sensorium commune." 18
In another paper Harvey gives an interesting account of parturition in " a young woman. ...in a profound state of coma .... but in whom the application of a powerful sternutatory ... excited convulsions throughout the body, beginning at the shoulders and gradually descending to the lower extremities. As often as the stimulus was applied the labour advanced . . . . until the child was born, without the consciousness of the mother, who still remained in a state of coma."
A hundred years after these words were written, Unzer developed the idea still further, in his Treatise on "Animal Nature in Relation to purely Animal Forces, or Vis Nervosa;" and after him Prochaska, in his "Dissertation on the Functions of the Nervous System," defined accurately the limits of the reflective centre; but it was left for Sir Charles Bell, and much more to our own distinguished Fellow, Marshall Hall, to expound the meaning of these movements; to compre- hend and reveal the physiology and pathology of action in the spinal cord; to apply this knowledge to the explana- tion of many diseases, and to devise means for their control or cure. In doing this, he again prepared the way for later researches upon the reflex function, as it affects "local" circulation, and so rendered possible a knowledge of many of the finest points of neural and vascular action, which we, directly, owe to the labours of those great workers to whom allusion has already been made, when
18 On Generation, p 432 et seq. 19 On Parturition, p. 535.
