244 PRACTICAL HISTOLOGY. [XX. 



artery. The lymphatics are not very numerous. For the nerves 

 see Lesson XVII. 7. 



8. Spleen. Tie the blood-vessels at the hilum of the spleen of a 

 cat, so as to keep the blood in the spleen. Cut it out and place it 

 in a large volume of Miiller's fluid (two weeks) or 2 per cent, 

 bichromate of potash. Wash it thoroughly in running water for an 

 hour or two. Cut out small pieces and harden them in alcohol. 

 Make transverse sections, i.e., across the long axis of the organ ; 

 stain one in logwood, and mount in balsam. Other sections are to 

 be stained in picro-carmine and mounted in Farrant's solution, and 

 a thin set placed in i per cent, osmic acid (twenty-four hours), and 

 mounted in Farrant's solution. This sharpens the outlines of the 

 elements. Stain other sections in eosin-logwood or safranin (forty- 

 eight hours). 



9. T.S. Spleen (|_) (Cat; li<jematoxylin or eosin and licematoxyliri). 

 The Malpighian corpuscles are visible as small blue spots to the 

 naked eye. 



(a.) Externally the capsule, fibrous, thick, firmly adherent and 

 closely applied to the organ, sends trabeculse into the spleen, where 

 they branch and anastomose to form a trabecular framework. Some 

 of them will be cut longitudinally, others obliquely, and some trans- 

 versely. In the larger trabeculse, sections of large blood-vessels 



Fro. 232. Elements of Human Splenic Fia. 233. Reticulum of 

 Pulp. i. Leucocytes ; 2. Epithelial the Splenic Pulp.; 



cells; 3. Coloured blood-corpuscles; 

 4. Cells containing pigment-granules. 



(fig. 231). Note that there is no lymph space between the capsule 

 and the gland substance, as is the case in lymph glands. 



(b.) Filling the interstices of this network, the splenic pulp, and 

 in it oval or rounded bodies Malpighian or splenic corpuscles 

 as blue-stained bodies contrasting with the yellowish brown pulp in 

 which they lie. In the centre of each is a lighter area, the "germ- 

 centre" of Flemming. In each corpuscle a section of a small 

 artery lying excentrically in the mass. The splenic corpuscles are 



