INTESTINAL OBSTRUCTION. I 77 



inally, and the inner layer of fibres placed transversely; by this 

 arrangement the muscular contractions, which are brought about 

 by a stimulus furnished from the nervous system, alternate, thus 

 producing first an enlargement and then a contraction of the tube 

 in consequence of which the alimentary contents are gradually 

 pushed on; it should be observed, however, that these said con- 

 tractions and dilatations of the tube proceed and follow one an- 

 other like the waves of the sea and are not continuous from one 

 end of the intestines to the other, as one movement; in this man- 

 ner the food passes slowly and steadily along the digestive canal, 

 meaijwhile mingling with its secretions and being absorbed, as 

 digestion is completed, through the various openings and blood- 

 vessels of the lining mucous membrane. In dealing with these 

 various forms of intestinal obstructions it may be as well to take 

 that which, in certain places, occurs very frequently, namely the 

 presence of a calculus (or .stone); in our experience these in- 

 testinal concretions, which vary in consistence from material 

 formed by the accumulation round a centre of undigestible prov^- 

 ender to that which is as hard and brittle as a flint and also in 

 bulk from the size of a small pebble to an ordinary cannon ball 

 are found more often in horses belonging to millers and corn 

 factors than anywhere else, and we attribute this to the probable 

 fact, that bran is a staple commodity of food with owners of this 

 class or trade; we could quote quite a number of instances, were 

 it necessary, in proof of this opinion, in which after discontinu- 

 ance of bran as an ordinary article of diet the presence of intes- 

 tinal calculi never thereafter w^as discovered, and certainly no losses 

 by death from this cause were experienced; inasmuch as bran con- 

 tains or consists of a very large proportion of mineral matter, it 

 is quite within the bounds of reason that the animal partaking of 

 undue proportions of this diet should be unable to assimilate a 

 chemical constituent of this character when the same was present 

 in superabundant quantities, and it is not improbable that a hind- 

 rance to its evacuation might arise by reason of the chemical 

 action of the intestinal secretions thereupon; hence the tendency 

 to accumulate and deposit around a nucleus, in the way of a 

 small nail, pebble or other foreign substance, such as are fre- 

 quently found in the large colon of the horse; and this formation 

 once established usually continues until one large calculus is 



