502 COMMENCEMENTS OF LYMPHATICS. [sect. 2 1 7. 



The commencements of the lymphatics are only known with 

 certainty in a single place, viz., in the tails of batrachian larvae, 

 where I discovered them in 184.6 (Annal. d. Sc. Natur., 1846), and 

 here (fig. 205) they are seen to possess essentially the same struc- 

 ture as the blood-capillaries. These capillary lymphatics, which 

 spread out in beautiful ramifications in the transparent edges of the 

 tail, from an upper and lower vas lymphaticum caudale, exhibit in 

 the trunks, as well as in the minuter vessels, a single, very delicate, 

 structureless coat, with nuclei upon its interior; and they are dis- 

 tinguished in their structure from the blood-capillaries of the larvae 

 solely by the presence of numerous fine- toothed processes of various 

 lengths proceeding from their membrane, so that they have a pe- 

 culiar sinuous appearance. The commencement, also, of these 

 vessels, o , oo2'" to croc^'" broad, is also peculiar, for they form but 

 few anastomoses, but commence almost always by fine pointed 

 extremities, even in the fully-developed tail (fig. 205). — In the first 

 edition of my German manual, I indicated two other situations in 

 which the commencement of lymphatics had been unequivocally ob- 

 served ; but these observations have again become doubtful by more 

 recent investigations. The vessels which were figured by me as 

 lymphatics in the trachea of man (Mikr. Anat., fig. 279), were pro- 

 bably nothing else than blood-vessels peculiarly metamorphosed. 

 Virchow, at least, has recently found vessels in the mucous mem- 

 brane of the trachea and intestine transformed into whitish widened 

 canals, filled with fatty granular masses, on which he observed, 

 also, terminations apparently caecal; and these vessels evidently 

 belonged to the sanguiniferous system ; an observation which, if 

 it does not completely invalidate my former views, yet deprives 

 them of all certainty. With regard, secondly, to the chyle-vessels 

 of the intestinal villi, I believe I can positively answer for them 

 here; but when an observer of the authority of Brilcke totally 

 denies their existence (see § 153), they can no longer be classed 

 among the number of well-established facts. If the commence- 

 ments of the chyle-vessels be not known in these places, it is 

 certain that they are not known in any other case, or in any other 

 place; and although the results of injections point to the com- 

 mencement of lymphatics by networks {Mikr. Anat., ii. 1, p. 22, 

 23), yet these have never yet been narrowly investigated with the 

 aid of the higher magnifying powers, and, in some parenchymatous 

 organs, no result whatever has yet been attained by means of 

 injections. 



The transition of the lymphatic capillaries into the larger lym- 



