LYMPHATIC AND LACTEAL SYSTEM. 



215 



injected the lymphatic vessels from the cellular 

 tissue, and most anatomists have remarked that 

 when an injection thrown into the bloodvessels 

 has extravasated into the cellular membrane, it 

 has occasionally entered the lymphatic vessels. 

 I have several times injected Fohmann's so 

 called lymphatic cells of the umbilical cord, 

 and have preserved a specimen shewing them, 

 but cannot acquiesce in the opinion that they 

 form a part of the lymphatic system. These 

 cells, which readily receive the quicksilver in- 

 troduced into a puncture made in the cord, 

 vary in diameter from l-100th to l-250th 

 of an inch, and communicate freely with 

 each other; they have a very regular and 

 organized appearance, but can only be injected 

 after putrefaction has commenced. Fohmann 

 describes them as situated between the lym- 

 phatics of the placenta, which terminate in them, 

 and those of the fetus, which commence from 

 them. I have never succeeded in pressing the 

 injection from the cells of the cord into the 

 lymphatics of the fetus or of the placenta. 

 Treviranus conceives that the lymphatics every- 

 where commence by elementary cylinders of 

 cellular tissue, and that in the villiofthe intes- 

 tines these elementary cylinders are so arranged 

 as to have one of their extremities terminating in 

 a lacteal vessel situated in the centre of each 

 villus, while the other reaches the periphery of 

 the villus, on the surface of which they present 

 little vesicular projections, in whose centre he 

 thinks he perceives a minute orifice. Arnold 

 also observed a similar arrangement of the cel- 

 lular tissue of the orbit into minute cylinders, 

 which he supposed to be an incipient net-work 

 of lymphatic vessels. Cruveilhier considers it 

 probable that the cellular tissue and the serous 

 membranes are formed of lymphatic vessels; 

 and Mascagni makes a more sweeping assertion 

 that all the white textures and the whole cel- 

 lular web of the body is composed of these 

 vessels. 



The opinion that the lymphatic system com- 

 mences by a plexus or net-work of vessels 

 larger than the capillary bloodvessels, and 

 which can always be seen by the unassisted 

 eye when injected, appears to be the best 

 supported by evidence, and to be that more 

 generally received by modern investigators. 

 These incipient plexuses are considered to 

 be destitute of orifices either on the villi or 

 elsewhere, and in this respect to resemble 

 the peripheral branches of the arteries, veins, 

 and excretory ducts, which, according to 

 the more recent views in minute anatomy, no 

 where present open mouths. The splendid 

 injections of Mascagni, Fohmann, Lauth, and 

 Panizza, shewing these vessels in various parts 

 of the body, on the interior of mucous mem- 

 branes, on the surface of particular portions of 

 the skin, on the serous membranes, especially 

 that part covering the solid viscera, on the 

 lining membrane of the heart and blood- 

 vessels, and of the excretory ducts of the 

 glandular viscera, offer a body of evidence 

 which can scarcely be resisted. In none of 

 these situations can open orifices be discovered 

 by the aid of the microscope or by means of 



urging on the injection. On the surface of the 

 liver, where the lymphatics may be injected 

 with great facility, by pressing in a retrograde 

 direction the injection may be forced beyond 

 the valves, and by continuing the force some 

 extremely minute globules of mercury may be 

 made apparently to pass through the coats of 

 the vessels. Haase has also, by the same pro- 

 cedure, forced the mercury through a net-work 

 of lymphatics on the surface of the skin ; but 

 these circumstances can hardly warrant the 

 supposition of lateral organized pores. These 

 primary networks of lymphatic vessels are said 

 to be deficient in valves in some situations. 

 The meshes of the networks are of various 

 forms and sizes : sometimes they are nearly 

 equal-sided, at others oblong or irregular ; in 

 some places the vessels are so closely set that 

 the spaces between them can scarcely be seen ; 

 in others they are larger and very distinct. 

 The plan adopted by Fohmann to display these 

 vessels, though liable to some objections, ap- 



Fig. 51. 





Shews an incipient plexus of lymphatic vessels. 



(from Breschet. ) 



a, the more superficial plexus formed of very 

 minute valveless vessels. b, a deeper plexus 

 formed of larger valveless vessels, which receive 

 the contents of the former, and which terminate in 

 lymphatic vessels armed with valves. 



pear's to be the most successful. He pierces 

 the part to be injected with a sharp-pointed 

 lancet, held nearly horizontally, so as to pro- 

 duce a very superficial wound, the lymphatic 

 net-work being generally nearer the surface 

 than the capillary bloodvessels ; into the wound 

 thus effected the pipe of the mercurial injecting 

 tube is inserted, and the quicksilver is made to 

 enter some of the vessels opened in the in- 

 cision, either by the weight of the column of the 

 mercury or by urging it on with the handle of a 

 scalpel. On the glans penis this method scarcely 

 ever fails to fill the lymphatics, which are of 

 large size. In the skin of the scrotum, and in 

 the neighbourhood of the nipple, success will 

 occasionally attend the attempt to shew these 

 vessels ; but in other parts of the integument, 

 the endeavour has with me always been fruit- 

 less, so much so that I cannot help doubting 

 their universal existence on the surface of (he 

 true skin. Breschet's description of a net- 

 work of lymphatics brought ii to view by 

 piercing the cuticle only, with a ( apillary tube 

 of glass connected with a columi of mercury, 

 I am convinced is deceptive : hi; words are 



