AND ITS APPENDAGES. 



777 



Fig. 288. 





undeveloped at the time of birth. The division of the colon into sacculi 

 by longitudinal and transverse bands, is also an appearance which pre- 

 sents itself only during the last half of foetal life. Previous to that 

 time, the colon is smooth and cylindrical, like the small intestine. 



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

 grows, at this time, faster than the walls of the abdomen ; so that it 

 can no longer be contained in the abdominal 

 cavity, but protrudes, under the form of an 

 intestinal loop, or hernia, from the umbilical 

 opening. (Fig. 288.) In the human em- 

 bryo, this protrusion of the intestine can be 

 readily seen during the latter part of the 

 second month. At a subsequent period, 

 the walls of the abdomen grow more rapidly 

 than the intestine ; and, gradually envelop- 

 ing 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, and 

 thus produces congenital umbilical hernia. 

 As the parts at this time have a natural 

 tendency to unite with each other, if the 

 hernial protrusion be returned within the abdomen, and retained by 

 simple pressure for a sufficient period, the defect is usually remedied, 

 and a permanent cure effected. The conditions are different in a hernia 

 in the adult, where it is due to pressure from within, and a gradual 

 yielding of the fibrous tissues. As the natural period for the closure 

 of the abdominal orifices has passed, the intestine may be retained 

 within the abdomen, in such cases, by mechanical means, but usually 

 escapes again when the pressure is 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, of a light yellowish or grayish-white color 

 in the duodenum, yellow, reddish-brown, and greenish-brown below. In 

 the large intestine they are dark greenish and pasty in consistency ; 

 and the contents of this portion of the alimentary canal 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, probably the residue of epithelial and mucous 

 accumulations. It does not exhibit any trace of the biliary substances 

 proper (taurocholates and glycocholates) when examined by Petteni- 

 kofer's test ; and cannot therefore be regarded as resulting from the 

 accumulation of bile. In the contents of the small intestine, on the 

 contrary, according to Lehmann, slight traces of bile may be found, as 

 50 



FCETAL Pio, showing the pro. 

 truding loop of intestine, forming 

 umbilical hernia; from a speci- 

 men in the author's possession. 

 From the convexity of the loop a 

 thin filament ia seen passing to 

 the umbilical vesicle, which, in 

 the pig, has a flattened, leaf-like 

 form. 



