SOME PHYSIOLOGICAL ASPECTS OF HYPNOTISM. 519 



central nervous masses as the spinal cord ? The line here 

 divides and the impulse thus scatters ; part may go on up to 

 higher portions, but part may travel along the short processes 

 until it reaches their terminations and arrives at the gaps. 

 There it may end, since the line ends ; but it may force the 

 gap, struggling through it. In doing this the most obvious 

 fact is the extra time involved in such passage. An impulse 

 takes only wo sec. to travel up i 2 inches of nerve-fibre, it 

 takes, under the most favourable conditions, at least another 

 T^o sec. to struggle across the microscopic gap. For this 

 struggle it may be inadequate and be thus extinguished, but, 

 if it succeeds and reaches the shore of the cell from which 

 the down line starts then it travels rapidly along this to 

 the muscles, and muscular movement must ensue. This 

 is the physiological basis ol reflex action indicated in its 

 utmost simplicity and even the most complicated involun- 

 tary, that is automatic, movements must involve similar 

 central physiological processes. Two further aspects of 

 these processes remain to be referred to, since they form 

 the basis of those conceptions of the physiological changes 

 in the hypnotic state first put forward by Heidenhain and 

 by Preyer. One of these aspects is associated with the dis- 

 tribution of the structural path ; on the ingoing or sensory 

 side the lines divide many times and thus the ingoing im- 

 pulse is conveyed to many regions ; it may thus struggle 

 through gaps in many different situations, and emerge, along 

 various outgoing motor lines, to widely separated organs. 

 This is the physiological expression of the familiar ex- 

 perience that an ingoing nerve-impulse (such as that caused 

 by a prick on the skin) can spread and emerge so as to 

 produce movements of distinct groups of muscles, in arms, 

 legs and larynx. The second aspect is due to the struggle 

 necessary to force a passage through the gap ; the physi- 

 ological path here offers a resistance, hence an ingoing im- 

 pulse, if weak, may result in no obvious movement. Unable 

 to force the gaps, it has been extinguished at the ends of 

 the ingoing tracts ; it has perished in the attempt to cross 

 this unknown region. When once such an impulse has 

 struggled across the gap, nothing can stop its further pas- 



