THE INTESTINE. 217 



CHAPTER XV. 



THE SMALL AND LARGE INTESTINE. 



Preparation 1. Sections of small intestine. 



Pieces of the small intestine are to be prepared in 

 exactly the same way as the stomach, the mixture 

 of alcohol and chromic acid solution being employed 

 to distend the gut, which is then immersed in the 

 fluid. After a few hours the intestine is opened arid 

 the fluid changed, and in three or four days the tissue 

 is transferred to spirit, to complete the hardening. 

 Three pieces of the small intestine are to be pre- 

 served in this way, viz., one from the very com- 

 mencement of the duodenum (this will probably have 

 been included in the stomach preparation) ; a second 

 from the jejunum ; and the third from the ileum, in- 

 cluding one of the patches of Peyer. The pieces 

 may be obtained from a cat, dog, or rabbit, the con- 

 tents of the intestine being first washed out by forc- 

 ing a rapid stream of the alcohol and chromic fluid 

 through them before tying up the further end. 

 Instead of distending it with the preservative fluid, 

 the gut may be opened and kept in an extended 

 state by pinning it on a cork or cake of wax, which 

 is then inverted into the fluid. 



In embedding the small intestine in wax- mass 

 care should be taken that the inner surface does not 

 retain too much spirit between the villi, for this 

 would prevent the melted wax-mass from penetrat- 

 ing between them, so that they are thus left without 

 a support whilst being cut. At the same time the 

 surface should on no account be allowed to become 

 quite dry. 



It is necessary, in order to see the structure of the 

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