DEVELOPMENT OF LYMPHATIC GLANDS. 97 



that the first rudiment of a lymphatic gland is a collection of 

 embryonic tissue, very highly vascularised, which forces its way 

 between the fibres of the surrounding connective tissue, thereby 

 forming for itself a capsule. It is only after this has taken 

 place that a clear sub-capsular space appears at its periphery, 

 and interstitial fissures become visible in its interior ; the latter, 

 by their connexions with the peripheric zone, partitioning the 

 gland-substance proper into follicular cords and terminal nodules 

 in the usual way. From a purely physiological point of view, 

 the lymphatic gland presents itself as a local dilatation of the 

 lymph-path, filled with a new and peculiar kind of tissue — the 

 ^^ymphadenoid tissue." This is made up of lymph-corpuscles 

 embedded in the well-known reticulum ; it is held to be the 

 great breeding-ground for the colourless corpuscles of the 

 blood ; and as it is generally agreed that the red corpuscles are 

 evolved from the colourless ones, and that the migratory cells of 

 the connective tissue are colourless corpuscles which have escaped 

 from the vessels, the tissue of the lymphatic glands may be 

 regarded as the common source of all the mobile cells of the 

 entire intermediate apparatus of nutrition. Unfortunately how- 

 ever, this hypothesis, like many others on the genesis of tissues, 

 still rests on an uncertain basis. We must admit that the lymph- 

 corpuscles in the glands have hardly ever been seen to divide, 

 the assumption reposing mainly on the old and readily demon- 

 strable observation, that the lymph contains fewer corpuscles 

 before its passage through the glands than after it. But may 

 not this increase in the number of corpuscles be due to emigra- 

 tion from the blood-vessels ? There seems to be no reason why 

 leucocytes should not escape from the vessels in a lymphatic 

 gland as well as in any other organ ; nay, the very fact that the 

 lymph-corpuscles are most abundantly generated during the 

 digestive hyper^emia of the alimentary apparatus, in which, as 

 wc all know, the lymjihatic glands take a conspicuous share, tells 

 rather in favour of this theory than against it. For my own 

 part however, I would rather not try, on such grounds as^^these, 

 to overthrow the doctrine which has attained right of citizenship, 

 and which is so very plausible a priori, that new cells originate 

 in the lymphatic glands by fission of the lymph- corpuscles. I 

 continue to regard the lymphatic glands as organs, which the 

 intermediate apparatus of nutrition may be said to construct for 



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