io8 PRACTICAL HISTOLOGY. 



in the microtome imbedded in paraffin. The sections are 

 mounted in Farrants' solution or in glycerine. They may 

 be unstained or stained with logwood. This dye is especi- 

 ally useful for mapping out the splenic corpuscles. 



b. For the study of the splenic pulp, it is advantageous 

 to place small portions of perfectly fresh spleen in one per 

 cent potassium bichromate solution for five or six days, and 

 then to make sections in the freezing microtome. It is 

 difficult to get good sections of the spleen by freezing when 

 it has not been previously hardened by other methods, but 

 the difficulty is entirely overcome by impregnating the tissue 

 with a thick solution of gum previous to freezing ( 309). 

 The blood corpuscles may be removed from the adenoid 

 tissue of the pulp by gently shaking the sections with salt 

 solution in a test-tube, as recommended for lymphatic 

 gland ( no). 



c. The cell elements of the spleen may be examined in 

 the fresh condition in aqueous humour. 



174. Structure. Examine, without the microscope, the 

 cut surface of the fresh spleen of ox. The tough fibrous 

 capsule is evident. Scrape away the pulp, and observe the 

 branching cord-like trabeculae continuous with the capsule, 

 and running from one surface to the other of the organ. 

 Look at a cut surface that has not been scraped, and en- 

 deavour to see the splenic corpuscles minute things like 

 millet seeds, or like very small grains of unboiled sago. 

 The cut ends of the trabeculae must not be mistaken for 

 them. Endeavour to pick out a splenic corpuscle with the 

 point of a scalpel. They are generally attached to the 

 tunica adventitia of the arteries. It is sometimes possible 

 to pull out a small artery, and see the corpuscles adhering 

 to it like small I beads. The structure of the spleen is 

 somewhat analogous to that of a lymph gland. The cap- 

 sule and trabeculae are similar. The splenic corpuscles 

 apparently correspond to the follicular tissue of the latter, 

 while the splenic pulp may be compared to the lymph 

 sinus. In the spleen, however, blood-vessels open into the 

 spaces amidst the adenoid tissue of the pulp, to which they 

 appear to be related in a manner similar to that. of the 



