BLOOD-VESSELS OF THE SPLEEN. 



205 



lob-sided. They are not surrounded by any special envelope, 

 some animals the lymphatic 

 tissue is continued for some 

 distance along the small 

 arteries, so that to some ex- 

 tent it resembles a peri- 

 vascular sheath of adenoid 

 tissue (W. Miiller, Schweig- 

 ger-Seidel). In a well injec- 

 ted spleen, a few fine capillaries 

 may be found within these 

 corpuscles (Sanders). The 

 capillaries distributed in the 

 substance of the Malpighian 

 corpuscle (Fig. 90) form a 

 net-work, and ultimately pour 

 their blood into the spaces in 

 the pulp. According to Ilobin 

 and Legros, these vessels are 

 comparable to the vasa vaso- 

 rum of other blood-vessels. 

 According to Cadiat, the 



In 



Fig. 90. 



Malpighian "corpuscle of the spleen of a cat 

 injected a, artery around which the 

 corpuscle is placed ; b, meshes of the pulp 

 injected ; c, the artery of the corpuscle 

 ramifying in the lymphatic tissue composing 

 it. The clear space around the corpuscle is 

 the lymphatic sinus. 



corpuscles are separated from the splenic pulp by a lymphatic sinus, 

 which is traversed by efferent capillaries passing to the pulp (Fig. 90).] 

 Connection of Arteries and Veins. It is very difficult to determine 

 what is the exact mode of termination of the arteries within the spleen, 

 more especially as it is extremely difficult to inject the blood-vessels of 

 the spleen. According to Stieda, W. Miiller, Peremeschko, and Klein, 

 the fine "capillary arteries" formed by the division of the small 

 arteries do not open directly into the capillary veins, but the connec- 

 tion between the arteries and veins is by means of the " intermediary 

 intercellular spaces" of the reticulum of the spleen, so that according to 

 this view, there is no continuous channel lined throughout by epithelium 

 connecting these vessels one with another. Thus the blood of the 

 spleen flows into the spaces of the adenoid reticulum just as the lymph- 

 stream flows through the spaces in a lymph-gland. According to 

 Billroth and Kolliker, a closed blood-channel actually does exist 

 between the capillary arteries and the veins, consisting of dilated 

 spaces (similar to those of erectile tissue). These intermediary spaces 

 are said to be completely lined by spindle-shaped epithelium, which 

 abuts externally on the reticulum of the pulp. [According to Frey, 

 owing to the walls of the terminal vessels being incomplete, there 

 being clefts or spaces between the cells composing them, the blood 



