CHAPTER XVII 



A TRANSPORT SYSTEM OF A PECULIAR KIND 



In the preceding chapter we have seen how food is taken 

 into the mouth, where it is pulped, rolled into suitable 

 packages or boluses, and then by a piston-like action of 

 the tongue the bolus is thrust within the pharynx where 

 it is set out on a 28-foot journey, one which, under the 

 most favourable circumstances, will extend over a period 

 of at least 24 hours. In this chapter we are to follow 

 the progress of a single bolus — the first spoonful of a 

 dish of porridge of a peculiar kind, one known to modern 

 physicians as a " test meal." It is mixed or impregnated 

 with a tasteless, harmless salt of bismuth, and is given to 

 patients when there is suspicion that the transport arrange- 

 ments of their alimentary systems have broken down or 

 become deranged. A bolus so impregnated is opaque to 

 X-rays and hence its progress can be followed as it is 

 carried from alimentary to alimentary factory, when the 

 body of a living patient is transilluminated by the help of 

 an X-ray apparatus. The bolus we are to follow in this 

 chapter is to be dispatched at 8 a.m. prompt from the 

 mouth of an accommodating friend. We are to have at 

 hand not only the outfit to illuminate his body and so 

 watch the meanderings of the bolus-shadow, shaped like 

 an overgrown tadpole, as it is transported along his 

 alimentary tract, but we shall also have at our disposal 

 actual examples of the machinery employed so that from 

 time to time we may examine the various parts of the 

 canal through which we have watched the bolus pass. 

 We are to concern ourselves chiefly with the management 



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