LYMPHOID ORGANS. 



119 



only its cell borders are, by way of exception, not cemented 

 to each other. If we also add to this that capillaries run in 

 the axis of the pulp strands, and that in the narrow reticulum 

 of its tissue regular red blood corpuscles are met with, some- 

 times fresh and unchanged, sometimes shrivelled and in va- 

 rious stages of disintegration, we have then described the 

 most essential portion of the structure of the tissue of the 

 spleen. 



In order, however, to gain a further insight, we must now 

 turn to the vascular arrangement of this strange organ. 



This is very complicated and quite peculiar, and it is just 

 here that the views of investigators are diametrically opposed 

 to each other. 



The arteria lienalis buries itself, in the ruminantia unrami- 

 fied, otherwise, as a rule, with several branches, directly into 

 the so-called hilus. The latter become further divided in the 

 interior, and finally break up, at an acute angle, into a number 

 of fine terminal branches. These, called penicilli, and pecu- 

 liarly formed, resemble the branches of a willow stripped of 

 its foliage. On these branches (but no longer on the penicil- 

 lus) sit the familiar Malpighian corpuscles, like the berries on 

 the stem of the grape. 



The arteries and the veins are still invested by a connec- 

 tive-tissue sheath, which is continuous with the septum sys- 

 tem of the organ. This sheath, like the entire vascular 

 expansion, is very different in the several varieties of animals; 

 it is slight and rudimentary in the small, complicated and 

 thick in the large mammalia. 



Pausing now, however, at that of man, we find the arteries 

 and veins, already divided into 4 to 6 branches, passing in and 

 out of the organ. Up to trunks of 0.2 mm. they are invest- 

 ed in common by a connective-tissue sheath. The latter has 

 at first a parietal thickness of about 0.25 mm., diminishing 

 to O.i mm., whereby arteries of 0.2 and veins of 0.4 mm. 

 are still invested in common. There is now a gradual sepa- 

 ration of the venous from the arterial branches. The sheath 

 in its original condition is continuous for a less distance over 



