674 



REPRODUCTION. 



FIG. 225. 



bilical vesicle, which, jp the pig, 

 has a flattened, leaf-Uke form. 



died, and a cure effected. 



After the small intestine is formed, it increases rapidly in length. 

 It grows, for a time, faster than the walls of the abdomen ; and as it 

 can no longer be contained in the abdominal cavity, it protrudes, 

 under the form of a hernia, from the umbilical opening. (Fig. 225.) 



In the human embryo, this protrusion con- 

 tinues during the latter part of the second 

 month. Subsequently, the walls of the ab- 

 domen grow more rapidly than the intes- 

 tine ; and, gradually enveloping the hernial 

 protrusion, at last reinclose it in the cavity 

 of the abdomen. 



Owing to imperfect development of the 

 abdominal walls, and incomplete closure of 

 the umbilicus, the intestinal protrusion, 

 which is normal during the early stages of 

 foetal life, sometimes remains at birth, pro- 

 FCETAL PIG, showing the protrud- ducing congenital umbilical hernia. As 



ing loop of intestine, form- tne parts at thig time naye a natura l ten- 



ing umbilical hernia. From the i 



convexity of the loop a thin fiia- dency to unite with each other, if the hernial 

 ment is seen passing to the urn- p ro trusion be replaced within the abdomen, 

 and retained there by simple pressure for a 

 sufficient period, the defect is usually reme- 

 The conditions are different in the adult, 

 where hernia is usually due to gradual yielding of the fibrous tissues 

 under pressure from within. As the natural period for the closure of 

 the orifices has passed, though the intestine may be retained within 

 the abdomen, in such cases, by mechanical appliances, it again protrudes 

 when they are taken off. 



The contents of the intestine, which accumulate during foetal life, 

 vary in different parts of the alimentary canal. In the small intestine 

 they are" semifluid in consistency, yellowish or grayish-white in its 

 upper part, yellow, reddish-brown, or greenish-brown below. In the 

 large intestine, where they are of a dark greenish color and pasty in 

 consistency, they have received the name of meconium, from their 

 resemblance to inspissated poppy-juice. The meconium contains a 

 large quantity of fat, as well as various insoluble substances, the resi- 

 due of epithelial and mucous accumulations. It exhibits no trace of 

 the biliary salts (taurocholates and glycocholates) when examined by 

 Pettenkofer's test ; and cannot therefore be regarded as an accumu- 

 lation of bile. In the small intestine, on the contrary, according to 

 Lehmann, slight traces of bile may be detected as early as the fifth or 

 sixth month. We have found distinct indications of bile in the small 

 intestine at birth, but it is always in extremely small quantity, and 

 sometimes altogether absent. 



The contents of the foetal intestine are therefore mainly derived from 

 its mucous membrane. Even their yellowish and greenish hue does 

 not depend on the secretions of the liver, since the yellow color first 



