NO. l6 DUCTLESS GLANDS OF THE ALLIGATOR REESE 9 



ing from the capsule towards the center of the gland. The only 

 indication of trabeculae is an occasional strand of connective tissue 

 extending a short distance into the pulp and lying almost parallel to 

 the inner surface of the adjacent capsule (fig. 12, /). 



The main body of the organ is, of course, made up of the splenic 

 pulp (/>) to be described later, as seen under higher magnification. 

 Under this low magnification the pulp consists of a fairly dense mass 

 of small cells among which are scattered numerous Malphigian cor- 

 puscles (m) and large numbers of conspicuous yellow masses (y). 



The Malphigian corpuscles vary much in size in the same spleen 

 and in number in dififerent spleens ; the inclosed artery is usually quite 

 distinct. An occasional blood vessel (bv) of larger size is seen in the 

 splenic pulp. 



When examined under fairly high magnification several kinds of 

 cells are seen to make up the splenic pulp (pi. 2, fig. 13). The most 

 striking objects are the yellow cells noted above. They vary greatly 

 in size from that of one of the regular lymphoid cells to ten times 

 that bulk. Their color is a distinct brownish yellow, so tliat they 

 stand out in strong contrast in sections stained in haematoxylin and 

 eosin. They are non-granular and exhibit no nuclei, the only visible 

 internal structures being faint, irregular lines that seem to divide the 

 cell into irregular parts (7). Some of them seem to have a cell wall, 

 but most of them, on close inspection, give the impression of being 

 merely close agglutinizations of smaller, yellow masses. What these 

 yellow masses are it is difficult to imagine, unless they are aggluti- 

 nizations of disintegrating erythrocytes, though in this case it would 

 seem that some nuclei should be in evidence unless the nucleus is the 

 first part of the cell to disappear. Similar bodies have been described 

 in the mammalian spleen as " extracellular pigment granules," prob- 

 ably originating from disintegrating erythrocytes. 



The most numerous type of cell in the spleen is, of course, the 

 small lymphoid cell {2). These cells are usually round or oval in 

 outline, though some are quite irregular ; they contain a few granules 

 that take the haematoxylin stain readily, thus giving the distinct blue 

 color to the section as a whole. 



Scattered throughout the spleen are numerous erythrocytes (;?) 

 seen both flat and in profile. 



Occasionally a large, polynuclear cell may be seen (4) with two 

 or more nuclei, and more often a large, finely-granular cell with no 

 visible nucleus (5). 



