HERNIA. 385 



If the escape of the fluid should stop or diminish, a blunt 

 Btylet can be introduced into the canula to clean it of any albu- 

 minous or epiploic mass which may obstruct it. The operation in 

 small animals is performed ia the same manner. 



As the removal of the entire accumulation of the fluid is dan- 

 gerous, though less so than in thoracentesis, it is better to permit 

 a portion of it to remain. The quantity is sometimes enormous, 

 ranging between thirty-five and ninety-six quarts. After the 

 quantity desired has been obtained, the canula of the trocar is 

 carefully withdrawn, and a bandage or roUer of adhesive plaster 

 placed around the body of the animal. 



Among accidents possible m this operation, wounds of blood- 

 vessels or of the intestines, and fatal peritonitis may be men- 

 tioned. 



HEENIA. 



GENEEAii View. 



In a general sense, any tumor formed by the entire or partial 

 escape and protrusion of an organ, either whoUy or in part, from 

 the restraining tension of the integuments, or from the cavity 

 which forms its normal location, is a hernia, or in popular phrase, 

 a rupture. The more special appUcation of the term is to the dis- 

 placement of the abdominal viscera, but it is also employed to 

 describe the encephalocele, or protrusion of the brain through the 

 cranium; the projection of the iris and ih.e jabot, or protrusion of 

 the cesophagal mucous membrane, through its muscular coverings. 

 And again the prominence of a synovial membrane beyond its 

 ordinary bounderies: that of a muscle through its aponeurotic 

 envelope; the prolapsus of the rectum; of the vagina; of the 

 uterus, etc., etc., — -these also receive the same designation and are 

 recognized members of the hernia family. We shall, in the pres- 

 ent chapter, mainly limit our consideration to the displacements of 

 the abdominal digestive organs. 



The rationale of the formation of a hernia becomes a matter 

 of easy comprehension, when we take into consideration the gen- 

 eral anatomy of the abdomen, and especially the structure of its 

 inferior wall. The muscular layers which form the exterior wall 

 of this large splanchnic cavity are not of equal density through 

 their whole extent, and consequently do not offer in every part an 

 equal amount of resistance to the outward pressure of the interior 



