62 INTESTINAL MEASUREMENTS 



structure. It is held by Gegenliaui- that this organ is the 

 e(|uivalent of the reptilian tongue, and that in the skeletal 

 vestiges which it contains are to be found the equivalents of the 

 hyoid skeletal cartilages which support the tongue in lizards. 

 In this case the tongue of nianinials is a subsetjuently added 

 structure. 



The ocsopliagas leads from the mouth cavity to the stoi/icr/i. 

 The latter organ has commonly a distinctive shape in mammals. 

 This is well shown in Man. The orifices of the oesophagus and 

 intestine are somewhat approximated ; and this causes a bulging 

 of the lower border of the organ, usually spoken of as the greater 

 curvature. A stomach of this typical form is found in many 

 onlers of mammals, and is luilike the stomach in any of the 

 groups of lower vertebrates in shape. Sometimes the shape of 

 the organ is greatl)^ altered : it may be drawn out, sacculated, 

 or divided, as in the Iluminants and Whales, into a series of 

 differentiated chambers, each of which plays some special part in 

 the phenomena of digestion. 



The -intestine of ma.mmals is always long a nil much coiled, 

 though the length and conse([uent degree of coiling naturally 

 varices. On the whole it is perhaps safe to say that it is shorter 

 in carnivorous than in vegetable-feeding beasts. Thus the Paca 

 has an intestine of 39 inches total length, while the Oat, an 

 animal of about the same size, has an intestine which is only 

 36 inches long. A fish diet, howe^■er, to judge from the Seals, 

 is associated with a, long intestinal tract. The intestine is 

 di\'isil)le in the vast majority of inannnals into a small and a 

 large intestine. The two are sepai-ated ]»y a, valvular constriction 

 save iu certain Oarnivores ; and in the majority of cases the 

 distinction is also emphasised T)y the presence at the junction of 

 a blindly-ending diverticulum, the (■(iccnm. This latter organ 

 varies greatly in length, being very short in the Oat-tribe and 

 exceedingly long in Rodents. Its size is, to some extent, de- 

 pendent upon the flesh -eating or grass -eating propensities of 

 the animal in which it occurs. One of the longest caeca is 

 possessed by the Vulpine rhalanger, in which the organ is one- 

 tifth of the length of the small intestine ; while the opposite 

 i^xtremity is readied by Felis maeroscelis, which has a small 

 intestine one hvnidred times the length of the caecum. 



An interesting Y)oint in connexion with the gut of mammals 



