406 MANUAL OF HISTOLOGY. 



break up entirely, and their contents pass out at the periphery 

 of the corpuscles into the meshes of the pulp. It is to be 

 noted that the Malpighian -corpuscles are the only parts of the 

 spleen where capillaries exist to any extent. The arteries going 

 to the pulp for the most part break up at once. 



The spleen-corpuscles differ from the lymph-follicles, par- 

 ticularly, in having fewer capillaries, no lymph-paths, and in 

 containing pigment in their meshes. The number of Malpig- 

 hian corpuscles in a spleen of ordinary size, as estimated by 

 Sappey, is about ten thousand ; but this applies to lower ani- 

 mals. In man they are smaller and less numerous. Pro- 

 tracted disease is thought to dimmish the number. 



The spleen-pulp. This is a soft, reddish brown substance, 

 looking, when squeezed out, like grumous blood. On expo- 

 sure to the air it acquires a redder hue. Under the microscope 

 it is found to present a honeycombed appearance, in the meshes 

 of which are numerous lymph-corpuscles, fragments of red 

 blood-corpuscles, so-called nuclei, and pigment-granules. Thus, 

 we have really only a modified form of adenoid tissue. Klein 

 considers that the network is made up of the large, flat endo- 

 thelioid cells above referred to. Processes branching from 

 these and uniting with each other form the meshes. I have 

 been unable to make out the structure as Klein describes it, 

 and his own observations and plates do not demonstrate it 

 satisfactorily. The branching endothelioid cells'are connected 

 with the breaking-up and the beginning of the blood-vessels, 

 but do not form the whole pulp reticulum. 



The fibrillse of this retiform tissue are connected with the 

 external surface of the Malpighian corpuscles, with the lym- 

 phoid tissue that ensheaths the small arteries, with the fibrous 

 trabeculse of the spleen itself, and with the cell-nuclei of the 

 walls of the arterioles, capillaries, and venous radicles. From 

 these points they branch and interlace, enclosing the cellular 

 and other elements in their meshes. These branching fibrillse 

 are, as in other lymphoid tissue, of a pale, granular appearance. 

 The cells enclosed in the meshes are not crowded so closely 

 together as are those in the Malpighian corpuscles (Fig. 174). 

 They are of different sizes ; the small ones are sometimes de- 

 scribed as free nuclei. The larger ones have one, two, or more 

 nuclei within them. These larger cells often contain red blood- 

 globules in various degrees of disintegration, a fact which gives 



