322 SPECIAL HISTOLOGY. 



the case in the larger trunks, they usually appear small (0*002 

 — 0'003'"), closely investing the minute nucleus, and often 

 even, as it were, in process of formation by the apposition of 

 granules. As the chyle traverses the mesenteric glands, the 

 cells become more and more numerous and larger, so that in 

 the lacteals at the root of the mesentery (and also in the larger 

 lymphatic trunks), together with the small cells which are still 

 present, we find numerous larger ones, up to 00055"' in size. 

 At the same time, at any rate in the Dog, Cat, and Rabbit, a 

 multiplication of the lymph-corpuscles by division takes place 

 more or less actively; in this process the larger cells elongate 

 till they attain a length of 0*006 — 0'008'", and when the nucleus 

 has divided, are separated into two by a median, circular 

 constriction. This proceeding does not usually occur at all 

 in the thoracic duct, and consequently the larger cell-forms, of 

 0*004 — 0'0055'", are here rare. In Animals, at all events, the 

 majority of the cells in this situation are larger than the blood- 

 corpuscles, that is to say, they are 00025 — O'OOSS'", whilst in 

 Man, at least as observed by Virchow and myself in an exe- 

 cuted criminal, they were invariably smaller (from 0002"' on 

 the average). The nuclei of these lymph-corpuscles, which are 

 imperceptible without the addition of acetic acid, were for the 

 most part single and round, occasionally, also, horse-shoe 

 shaped, or constricted in the middle, very rarely truly mul- 

 tiple. In other Mammalia, cells having nuclei disintegrated by 

 acetic acid, or naturally constricted and multiple (3 — 5 fold) 

 are very rare, omitting those in process of division; although 

 occasionally such occur even in considerable quantity. 



Red blood-corpuscles I have not as yet noticed in the human 

 chyle, when it has been carefully taken, and under normal con- 

 ditions ; whilst in animals these corpuscles almost always occur 

 in the thoracic duct in small quantity, and also frequently in 

 the lymph of certain organs, as of the spleen. As they do not 

 exhibit the slightest trace of a development within the lym- 

 phatics, I regard them as elements escaped from the blood- 

 vessels, and indeed, am of opinion, so long as direct connexions 

 between the two sets of vessels in the peripheral parts are not 

 shown to exist, that this passage is an accidental occurrence, 

 from the rupture of finer vessels, which, owing to the peculiar 

 structure of certain organs, as the spleen and lymphatic glands, 



