58 ADAPTATION AND DISEASE 



Sunday press, and in certain exalted circles which have their 

 centre in Park Lane, would never have arisen if we, physicians 

 and surgeons, had a fuller grasp of this truth ? In other words, 

 I am inclined to believe that not a few cases of apparent organic 

 joint disease are habit conditions. I have pointed out that 

 mucous colitis has the earmarks of a habit condition, while 

 as to tics and other convulsive movements of nervous origin, 

 and hysterical manifestations, if not based upon habit then 

 due for their continuance to habit, their name, like that of 

 the Gadarene devils, is legion. As to these nervous cases, it 

 has been recognized from Lamarck 1 onwards that it is easier 

 for nervous stimuli of different orders to travel along well-worn 

 paths, and that thus there becomes established a condition in 

 which a minimal afferent impulse travelling without interrup- 

 tion along a particular path suffices to set in action first one and 

 then another of a group of co-ordinated nerve centres, so that 

 a minimal stimulus may eventually produce a maximal result. 

 On the other hand, the act of inhibition, or arrest of the passage 

 of a given impulse, if repeated, would seem to oppose so strong 

 an obstruction to the passage of impulses along a particular 

 path that soon a maximal stimulus will produce no result. 

 Here there is no anatomical change, only a matter of habit. 

 Put the patient under an anaesthetic or otherwise remove the 

 inhibitory block, and now stimulus is followed by the normal 

 reflex muscular act.. Also, the longer the individual has been 

 the prey of a habit, the more difficult it is to bring about the 

 return to the normal. Here again our war experiences with 

 " shell shock " and the " fear neuroses " (as distinct from shell 

 concussion) are proving this point up to the hilt in the striking 

 difference obtained by immediate treatment behind the front, 

 as contrasted with treatment of the same order in special hospitals 

 in England, initiated weeks, and it may be months, later. 2 



Some of my readers may recall that I have applied this law 

 of habit to explain the metaplasias, the conversion under altered 

 environment of tissues of one order into those of another — of 

 normal connective tissue into bone or cartilage, of stratified 



1 Zoological Philosophy (translation by Hugh Elliot), Maomillan & Co., 

 Ltd., 1914, pp. 349, 350. 



1 Tide Sir John Collie's lecture at the Royal Institute of Public Health, 

 reported in the Times of June 14, 1917. 



