432 



MANUAL OF HISTOLOGY. 



venous blood. The former or pulp tubes, like the lymph tubes of the 

 lymphatic nodes, spring, in the first place, in great number, and with 



gradual transitions from the 

 surface of the follicles. Here, 

 as in the rabbit, Guinea-pig, 

 hedgehog, and marmot, they 

 may be, for the most part, 

 concentrically arranged, the 

 interspaces bounded by them 

 naturally corresponding in 

 direction. A similar origin 

 of the pulp cords from the 

 lyrnphoid infiltrated arterial 

 sheaths as well as from the 

 adventitise of the last rami- 

 fications of the arteries, 

 may also be recognised. 

 Eventually they are inserted 

 into the fibrous trabeculae of 

 the interior. 



The tissue of the pulp 

 tubes or pulp curds is a 

 Flg ' 420 ' modification of the reticular 



connective species, and is of very delicate texture (fig. 421). It presents 

 everywhere a reticulum usually of extremely fine fibres, but also of some- 

 what more expanded bands. In some of the nodal points nuclei appear 



to be imbedded, al- 

 though, owing to the 



J- g reat delicacy of the 



tissue, doubt still- 



bedded, or only ad- 

 herent externally. If 

 we now follow up the 

 connections of this 

 network towards the 

 follicles or thickened 

 points of the arteries, 

 we recognise the fact 

 that the reticulated 

 tissue of the pulp is 

 continuous with the 

 coarser and tougher 

 sustentacular matter 

 of these parts ; inter- 

 mediate forms exist- 

 ing between the two kinds. If we now examine with special care the 

 numerous venous passages, and the limitations of the pulp cords towards 

 them, we soon convince ourselves here also of the reticular character of 

 the tissue in question. If successful in obtaining a view of the floor of 

 one of these venous passages, as at c, we will soon come to the conclu- 

 sion and to this Henle was the first to direct attention that the tissue 



Fig 421. From the pulp of trie human spleen. The preparation has 

 been brushed out (combination), a, pulp cords with delicate re- 

 ticulated sustentaculiir substance: 6, transverse section of hollow 

 venous canals: c, longitudinal section of the same; d, capillary in a 

 pulp tube, dividing at e; f, epithelium of venous canals; g, side 

 view of the same; and h, transverse section. 



