230 SCIENCE PROGRESS 



the whole, and a certain duty towards itself. These duties 

 or actions are called the functions of the part, and according 

 as the duty is well or ill performed, the function is normal, or 

 defective, or disordered. The duty towards the rest of the 

 body, which may be termed the extrinsic function, varies 

 extremely with the nature of the part ; but the duty towards 

 itself, which may be termed the intrinsic function, is the same 

 in every part, and consists in making good the waste con- 

 sequent on the performance of its extrinsic function, in repair- 

 ing any structural damage that may be inflicted upon it, and 

 in repelling the attacks of injurious agents, whether chemical, 

 microbic, or cellular. 



It is often debated by novices in medicine — of established 

 practitioners few have the time, and fewer still the inclination, 

 to ponder general questions — but by novices in medicine the 

 question is often debated whether disorder of structure pre- 

 cedes disorder of function, or vice versa. Those who discuss 

 this matter mean by function the extrinsic function only, and 

 whichever conclusion they arrive at will not hold good when 

 intrinsic function is taken into the consideration. If the 

 intrinsic function is disordered or defective, the structure must 

 fall into disrepair, and be unable to perform with full efficiency 

 its extrinsic function ; so that in such a case, while disorder 

 of (intrinsic) function precedes disorder of structure, disorder 

 of structure precedes disorder of (extrinsic) function. Even 

 with respect to extrinsic function alone, the answer must 

 depend on the meaning that is attached to structure. The 

 (extrinsic) function of a part is seriously interfered with or 

 abolished if the blood supply of that part is seriously dimin- 

 ished or abolished ; but the structure, in any usual, and I 

 think proper, meaning of the word structure, cannot be im- 

 paired, for the function is resumed as soon as the blood supply 

 is re-established. 



However this may be, it often happens that from one cause 

 or another the function, either intrinsic or extrinsic, of a 

 part of the body is disordered or defective. It is imperfectly 

 performed ; and when this happens there is usually, perhaps 

 always, some sign or manifestation of the altered performance 

 of function. The sign may be perceptible to the patient alone, 

 as in the case of pain or deafness, or dimness of vision, or a 

 whoreson tingling ; or, like coma, it may be perceptible to 



