iv REFLEX ACTION 43 



it till I found myself on the ground. Yet I fell on my 

 hands, and my face and head were not touched. And the 

 throwing out of the hands is a complex action involving 

 the well adapted duly proportioned contraction of quite a 

 number of muscles. 



4. There are certain fallacious arguments against the 

 mechanical conception of reflex action which it will be well 

 to consider. Take first the fact of adaptation. Many 

 reflexes among the higher animals involve very complex 

 co-ordination of muscular movements, a definite order and 

 simultaneity of contractions, a careful adjustment of the 

 length and vigour of each contraction, and so forth. In 

 this respect the higher reflexes contrast very markedly 

 with the simple contractions of, for example, a muscle- 

 nerve preparation, or the slow withdrawal of a pseudo- 

 podium by a Rhizopod. 



" When the peripheral stump of a divided sciatic nerve is 

 stimulated with the interrupted current, the muscles of the leg 

 are at once thrown into tetanus, continue in the same rigid 

 condition during the passage of the current, and relax immediately 

 on the current being shut off. When the same current is applied 

 for a second only to the skin of the flank of a brainless frog, the 

 leg is drawn up and the foot rapidly swept over the spot irritated, 

 as if to wipe away the irritation ; but this movement is a complex 

 one, requiring the contraction of particular muscles in a definite 

 sequence, with a carefully adjusted proportion between the 

 amounts of contraction of the individual muscles. And this com- 

 plex movement, this balanced and arranged series of contractions, 

 may be repeated more than once as a result of a single stimula- 

 tion of the skin. When a deep breath is caused by a dash of 

 cold water, the same co-ordinated and carefully arranged series of 

 contractions is also seen to result, as part of a reflex action, from a 

 simple stimulus." 1 



All this, of course, only proves that the machinery, if it 

 is machinery, is complex, and well adjusted to its end. 

 Put a penny on a balance, and it weighs down the scale 

 by the simple action of the lever. Put it into the slot of 

 an automatic machine, and it produces a stick of chocolate 

 by I know not what complication of levers and cogs. 

 Complexity of adjustment does not take us out of the 

 region of machinery. 



1 Foster, I. p. 184. 



