HISTQLOGICAL DEMONSTRATIONS. 109 



lymphatics to the sinus of the lymph gland ; the arteries 

 pass into capillaries, some of which penetrate the splenic 

 corpuscles (W. Sanders). They all eventually open into 

 the spaces in the pulp, from which the venous radicles are 

 derived (W. Miiller). There are lymphatics in the spleen 

 around the blood-vessels, and in the trabeculae ; their mode 

 of origin, however, has not been fully investigated. 



175. Section of chromic acid spleen of cat stained 

 with logwood. Mount in Farrants' solution or in glycerine. 



(L.) Capsule. Trabeculae. Splenic corpuscles much 

 larger here than they are in the human spleen. The pulp. 



(H.) The trabeculas, chiefly consisting of elastic fibres ; 

 non-striped muscle is also present in them and in the cap- 

 sule. The splenic corpuscles, containing great numbers of 

 lymph corpuscles. The envelope consists of a delicate 

 condensed adenoid tissue. The pulp, consisting of adenoid 

 tissue, with numerous blood-corpuscles in its spaces. Lymph 

 corpuscles are probably produced in the splenic corpuscles, 

 and find their way into the pulp, and from thence by the 

 veins. 



176. If the pulp of the fresh spleen be examined in aqueous 

 humour, clear colloid masses containing coloured blood-corpuscles, 

 variously transformed, may be found. These are supposed to be cor- 

 puscles breaking up. Similar bodies may be found in the red marrow 

 of bone ( 129). 



177. Examine (L.) a preparation of injected spleen. 



178. Thyroid Gland. (L. and H.) Examine sec- 

 tions of human thyroid gland injected and uninjected. 



The uninjected gland is best hardened in Miiller's fluid for a month, 

 and then in methylated spirit for a fortnight. Preserve in Farrants' 

 solution, or in glycerine, or stain with carmine or logwood, and mount 

 in dammar. The injected gland may be hardened in j per cent 

 chromic acid for a fortnight, and then cut by the freezing method, 

 stained with logwood or carmine, and mounted in dammar. 



The gland consists of sacs imbedded in fibrous tissue. 

 The sacs are lined by a somewhat cubical epithelium. 

 They contain lymph corpuscles. They are not penetrated 

 by capillaries, as is the case with the splenic corpuscles. 

 In the human subject they are often found enlarged, and 

 filled with a colloid material. 



