L YMPHOID OR GA NS. 



117 



creatures, a rabbit (Fig. in), for instance. In the larger 

 mammals, this system of septa considerably impedes our com- 

 prehension of the relations, which is already difficult. 



The soft spleen tissue proper consists of two substances. 

 In the first place, we find, scattered throughout the entire 

 thickness of the organ, rounded, oblong or irregular structures 



Fig. nr. — Rabbit's spleen ; a, Malpighian corpuscles ; b, reticular frame-work of the pulp. 



of a whitish color. Sometimes they stand out sharply, at 

 others they can only be recognized with difficulty. In many 

 species of animals they are observed crowded, in others more 

 scanty. Their size slowly decreases in the smaller mammalia. 

 These are the Malpighian corpuscles of the spleen or — let us 

 say at once — the lymphoid follicles of our organ (a). 



Between them appears a very soft, and in consequence of 

 its immense wealth of blood, dark red mass, the so-called 

 spleen-pulp. The microscopic analysis of the same shows a 

 system of reticularly connected canals (&), which connect 

 adjacent Malpighian corpuscles with each other, and leave a 

 likewise retiform space — 01 cavernous system between them. 

 The pulp is, therefore, suggestive of the medullary substance 

 of the lymphatic glands, as are the Malpighian corpuscles of 

 the follicles of the latter. 



