268 THE ENGINES OF THE HUMAN BODY 



between the breakdowns of motor vehicles and human 

 machines, nor to point the lesson that careful driving and 

 periodical overhauling will secure safe running in both 

 cases. 1 am writing this chapter because it is in the 

 repairing shop that we learn the essential difference be- 

 tween machines of Nature's design and those of man's 

 invention. We are going to see that only Nature can 

 repair the machines which Nature has made. The good 

 physician and the skilled surgeon are only good and 

 skilled in so far as they know the way in which Nature 

 works her cures. They can assist her to such an extent 

 that it can be said justly and truly that they save life and 

 restore health. The skilled mechanic is in quite a differ- 

 ent position. He can do much more for his machines 

 because they have been designed and made by workmen 

 like himself. He designs, forges, and welds his bolts and 

 shafts, remetals his bearings ; he is no mere assistant to 

 a higher power, but a Vulcan in his own right. 



We can best understand the difference between the 

 repair of a motor car and a human machine if we cite a 

 few instances culled from actual practice. In an early 

 chapter we have compared the tendon (see Plate II.) of 

 the muscular engine which moves the heel to the con- 

 necting rod which unites the piston to the crank-pin of an 

 internal-combustion engine. Now, it is not a common 

 accident for the connecting rod to break or the tendon 

 to be ruptured, but it certainly does occur. The motor 

 car comes to a sudden halt ; the human machine can still 

 go limping along. Both machines have to go to a re- 

 pairing shop or hospital. In the repairing shop, if the 

 connecting rod is of a standard type and spare parts are 

 available, then repair is easy ; a new connecting rod is 

 put in place of the old. But the roadside repairer, if 

 he is really a motor-car surgeon, must be able to make a 

 new one or know how to forge, weld, and temper the 

 old. With the human machine two courses are open 

 to the repairer. If a skilled technician he will, like the 

 mechanic, expose the ruptured part, stitch its torn ends 

 together with silken loops, and then stitch up the opening 



