70 PRACTICAL HISTOLOGY. 



VERMIFORM APPENDIX. 



PREPARATION. Inject the walls of the vermiform appendix of a rabbit with a two 

 per cent, watery solution of Berlin-blue, which readily passes into the lymphatics. Harden in 

 alcohol, and make transverse sections. Stain them with picrocarmine, and mount in Farrant's 

 solution. 



EXAMINATION (L). Observe the masses of adenoid tissue, stained red, divided into an 

 inner and an outer set, and round each the lymph-paths filled with Berlin-blue. The masses 

 of adenoid tissue are exactly like Peyer's patches, and each arc is partially surrounded by a 

 lymph-stream, as indicated by the blue injection, none of which passes into the interior. This 

 space represents a lymph-sinus, so that the masses of adenoid tissue are partially suspended 

 in a lymph-stream. Exactly the same relation obtains in a Peyer's patch. {Indicate these 

 appearances in PI. XIV., Fig. 5.) 



LARGE INTESTINE. 



PREPARATION. After washing out the large intestine of a dog or cat, cut it into pieces 

 one inch square and harden them in chromic acid and spirit fluid for two weeks and complete 

 the hardening in spirit. Make transverse sections. Stain with logwood, and mount one in 

 dammar, and another in Farrant's solution. 



Vertical Section of the Large Intestine. (Logwood and dammar.) EXAMINATION (L). 

 Observe the mucous coat thrown into folds, owing to the contraction of the muscular coat. It 

 is devoid of villi. Observe the vertically set Lieberkiihn's glands, exactly like those in the 

 small intestine. (Indicate one in PI. XIV., Fig. 3.) Some of them are sure to be cut trans- 

 versely, when they present a honeycomb-like appearance. {Indicate this in 'PI. XIV., Fig. 4.) 

 Observe the sub-mucous and muscular coats, very like those of the small intestine. Per- 

 haps a solitary gland may be found in the sub-mucous coat with its apex projecting free into 

 the mucous coat. There is a well-marked muscularis mucosae in the mucous coat, which 

 is pierced by the solitary glands. 



In the preparation mounted in Farrant's solution, examine (H) the glands, both when 

 divided vertically and transversely, and observe the adenoid tissue laden with lymph-corpuscles, 

 between and supporting them. 



Solitary glands will be found in sections of the large intestine. They are simply masses 

 of adenoid tissue placed in the sub-mucous coat They are easily stained by the same 

 methods as directed for Peyer's patches (p. 69). 



Blood-vessels of the Large Intestine are prepared exactly in the same way as those of the 

 small intestine. Several years ago it was customary to use an opaque injection, which 

 gives a beautiful effect when the piece of intestine is mounted upon a dark ground with the 

 mucous surface uppermost, and illuminated by means of a condenser. The mouth of each gland 

 is surrounded by a plexus of capillaries, so that the injection presents a regular honeycomb- 

 like appearance. 



Similar preparations made of the gastric mucous membrane at first sight resemble that of 

 the large intestine. The gastric mucosa is recognised by the existence of small openings 

 at the bottom of the depressions, and the latter are not so regular as those in the large 

 intestine. 



