438 MANUAL OF HISTOLOGY. 



234. 



As regards the lymphatics of the spleen, it was for some time believed, 

 from the results of injection, that it only possessed such vessels on its 

 surface. These are situated underneath the serosa, and are arranged in a 

 very complex network, in the ox, sheep, and pig, formed of valved 

 vessels of considerable size (Teichmann, Billroth, Frey). In the first 

 animals mentioned these vessels may be easily injected, and are seen then 

 to present a number of bead- like dilatations at various points. 



From the fact that during injection of the external vessels the matters 

 employed for that purpose could not be forced into any deeper lymph 

 passages in the parenchyma of the spleen, and that it had been already 

 ascertained that the Malpigliian corpuscle is not possessed of anything 

 corresponding to the investing space of the lymph follicle, the spleen came 

 to be regarded as an organ analogous to the lymph nodes, but in which the 

 internal lymphatic passages are replaced by venous canals. The well- 

 known participation of the organ in the life of the blood, the entrance of 

 lymphatic cells into the venous stream, and the very probable destruction 

 of multitudes of red corpuscles within the organ, all seem to justify its 

 being declared a blood lymph gland (Frey). 



Of course, the denial just mentioned of the existence of internal 

 lymphatics led to contradictions of the older views, based upon the 

 stated entrance of absorbent tubes at the hilus of the organ, together with 

 the arteries and veins (Ecker, Koelliker, and others). While the super- 

 ficial lymphatics, namely, were found to contain a pellucid fluid, those of 

 the interior were stated to be filled with a coloured liquid reddened by 

 the presence of blood-cells. 



A few years* ago, however, TJiomsa demonstrated lymphatic vessels in 

 the horse's spleen, and moreover in communication with those of the 

 surface of the organ. They traverse partly the banded sustentacular 

 matter, following the ramifications of the veins, and partly the connec- 

 tive-tissue of the sheaths of the vessels, together with the stronger arterial 

 twigs, whose finer ramifications they completely ensheath eventually. 



Now, the statements of this talented observer have not the slightest 

 trace of inconsistency about them. Here, as elsewhere, we find muscular 

 and connective-tissue structures traversed by lymphatic passages, and, 

 owing to the lymphoid transformation which comes over these sheaths 

 continuous on the other hand with ordinary connective-tissue, the lymph 

 cells may be supplied to the fluid from such localities. 



But when Thomsa states, further, that the final ramifications of the 

 internal absorbents conduct eventually into the follicles and pulp, and 

 there clothe the individual lymph corpuscles and agglomerations of blood- 

 cells with ring-like passages, we cannot rid ourselves of the greatest doubt 

 upon the point, nor avoid regarding what he has observed as probably 

 the result of extravasation into a tissue we know to be so fragile. We 

 can hardly conceive it possible, that beside the almost ubiquitous blood 

 stream, unconfined by a definite wall, a similar lymph stream could have 

 room to exist, and such an extensive peripheral mixture of lymph and 

 blood would be without any analogy in all that has as yet been observed 

 in the body in the two systems. 



But whichever view, is correct, the significance of the spleen as a 

 blood lymph gland is by no means shaken. 



The ueroes of the spleen having their origin from the phxits lienalis of 



