794 



SPLEEN. 



instance, in the hilus of a large calf I found 

 only four trunks of lymphatics, which toge- 

 ther possessed a diameter of only 176-lOOOths 

 of a line ; while the interior of the spleen is 

 also poor in lymphatics, for, so far as I have 

 seen, the numerous plexuses of lymphatic 

 trunks in the coats of the spleen have no rela- 

 tion with the interior of the organ, but at 

 least the greater number of them belong 

 solely to the subserous areolar tissue. 



As to the distribution of the lymphatics in 

 the spleen, it may easily be seen, by observ- 

 ations on oxen, that they only follow the 

 course of the arteries, lying with these in- 

 side the sheaths; while the veins, which 

 take a solitary course, and (as was before 

 mentioned) possess no sheath, are also devoid 

 of these companions. I have not seen the 

 commencement of the lymphatics, yet I can 

 state for a certainty, that they have nothing 

 to do with the Malpighian corpuscles, since 

 these corpuscles are completely closed, as 

 was before mentioned. And, I will add, in 

 support of this my view, that the small arte- 

 ries which pass to" the Malpighian corpuscles 

 are no longer accompanied by lymphatic 

 vessels; at least microscopic examination 

 detects no trace of such vessels within their 

 sheaths. Just as little does the pulp possess 

 any lymphatics ; for if these, like the nerves 

 (see below), pass from the sheaths of the 

 arteries into the pulp, they would in such 

 a case be visible. And from what has been 

 said, I conclude that the lymphatic vessels of 

 the interior of the spleen belong wholly and 

 solely to the sheaths of the arteries, and not 

 in the least to the pulp or the Malpighian 

 corpuscles ; and thus that here they play pre- 

 cisely the same rather subordinate part which 

 they do in the liver, where they pertain to 

 the capsule of Glisson, and not to the glandu- 

 lar substance ; or as in the kidneys, in the 

 interior of which they only accompany the 

 bloodvessels. Concerning the structure of 

 the lymphatic vessels, I can only state thus 

 much ; that in the calf they possess, at least 

 in their main trunks, three membranes : 

 1. An epithelium similar to that of the arte- 

 ries ; 2. A circular fibrous membrane, com- 

 posed of two or three layers of very distinct 

 unstriped muscular fibres ; 3. An outer mem- 

 brane of white fibrous tissue. Valves occur 

 in the deep as well as in the superficial lymph- 

 atics. 



8. Nerves. The nerves of the spleen arise 

 from the splenic plexus, and accompany the 

 splenic artery as two or three interlacing 

 trunks, and divide in such wise at the giving 

 off of its branches, that each artery receives 

 one, or very frequently two nerves, which 

 accompany it, and here and there anastomose 

 with each other. The thickness of the primary 

 nervous trunks varies very much in different 

 creatures. Thus in the sheep, and especially 

 in the ox, they are of really a colossal size, and 

 taken all together, their diameter equals that 

 of the empty and contracted splenic arteries ; 

 while in man and the pig they are no way 

 remarkable in size, and are many times smaller 



than the arteries. These differences, which 

 led the earlier authors to speak of the splenic 

 nerves in similarly different expressions, were 

 at first altogether inexplicable to me, since I 

 could not understand why the spleen of one 

 animal should possess so much larger nerves 

 than another. On a more careful examin- 

 ation, the microscope gave a very simple and 

 unforeseen explanation. The uncommon size 

 of the splenic nerves of Ruminantia depends 

 solely on this, that the white fibrous tissue 

 of these nerves is disproportionally developed 

 in the shape of the so-called " fibres of 

 Remak," while it is much less prominent in 

 the same nerves of other animals. A com- 

 parison of the splenic nerves of the pig and 

 calf has taught me that if we limit our inquiry 

 to the number of primitive nerve fibres, scarce 

 any difference exists between the two sets of 

 nerves. But, on the other hand, the primi- 

 tive nerve fibres of the pig lie very closely 

 together, so that they cannot be numbered 

 without considerable trouble ; while as an 

 example of their condition in the calf, I will 

 adduce the following: The trunks of the 

 nerves entering the hilus were seven in number, 

 with a diameter of -57, '2, '048, -6, '48, '48, 

 6 (line) ; and they contained respectively only 

 28, 7, 6, 9, 13, 9, 22 primitive nerve fibres. In 

 the lower animals, the nerves may be followed 

 with the knife for a considerable distance into 

 the spleen, much further than in man ; and 

 with the help of the microscope, I have very 

 frequently followed them even on the arteries 

 which go to the Malpighian corpuscles. I 

 have been just as little able as Remak to find 

 any ganglia on the arteries in the interior of 

 the spleen. Concerning their mode of termi- 

 nation, I am only able to say thus much ; 

 that the nerves also pass into the pulp, and 

 may even be easily seen on the pencils of 

 arteries, and finally that they disappear as 

 very small branches of not greater size than 

 the smallest capillaries ; but I am unable to 

 decide whether they terminate by means of 



Fig. 539. 



A very small nerve from the Spleen of the Calf, with- 

 out any visible primitive nerve fibres, and apparently 

 consisting only ofneurilemma (or fibres of Remak). 

 Magnified 350 diameters. 



