122 WARFARE IN THE HUMAN BODY 



factors of all functions, and we may expect them in every 

 nervous mechanism. What occurs abnormally is often the 

 roughest guide to the normal. But, if it is taken as normal, 

 physiology pays the penalty in confusion, even though it 

 should always regard pathology as its nearest relative — an 

 erring sister. 



When it is remembered that no science can explain 

 itself, and that knowledge is a patterned web woven out of 

 all the sciences, it also seems that biology, and the whole 

 course of evolution, might be more frequently referred to in 

 physiological work than is usual. It was suggested above 

 that reciprocal innervation may thus be looked on as a 

 biological evolutionary process, a case in which muscles 

 grew up together as interdependent organs in which alter- 

 nate actions, however now regulated, were a sine qua non 

 of their existence. Knowing as we do the moulding 

 effects of stresses on bone, and the facts that the sclero- 

 blasts of sponges settle and work about non-vibrating 

 points, biology and physics may work together even in 

 such problems, and suggest that quasi-nervous effects may 

 be produced in muscle, not only by alternate stretching and 

 contraction, but also by stresses communicated through 

 and by bone and other cells. Thus, quite independent of 

 so-called inhibitory fibres, a sudden powerful contraction 

 of one muscle might throw another out of action by giving 

 such intensely sensitive cells a signal of positive relaxation. 

 It is not so long ago that the rhythmic action of opposed 

 muscles was supposed to be due to direct innervation, not 

 to alternate reflex contraction and stretching. It seems at 

 times as if more was attributed to nervous action than is 

 actually due to it. 



It has been objected to some of these views that 

 excitation and inhibition are simple concepts, even if we 



