

ARRANGEMENT OF THE LYMPH PATHS. 339 



This view of the mode of origin of the lymphatic glands, 

 which is similar to that formerly proposed by Engel and 

 others, agrees but little with the recent observations of 

 Sertoli, who found that lymph canals lined with epithelium 

 first made their appearance ; around these the connective 

 tissue increased ; and in this, and consequently external to the 

 original lymph path, accumulations of cells occurred to form the 

 follicular glandular substance. 



The structural arrangements here described as existing in the lym- 

 phatic glands can be most easily recognised in the glands of the ox and 

 sheep. The glands of other mammals, and of man, present difficulties 

 which are easily set aside if the fundamental structure of the lymphatic 

 glands, as we now understand it, proves to be correct. In the lympha- 

 tic glands of oxen, the lymph path and follicular tissue may be dis- 

 tinguished with precision, (1) because the fibrous framework of the 

 lymph path is beset with pigment both in the medullary and the 

 cortical substance, whilst the follicular tissue is colourless ; (2) because 

 the follicular tissue through the entire medullary substance forms 

 continuous uninterrupted cords, which for the most part exceed the 

 lymph paths in breadth. In the lymphatic glands of man and the 

 dog the relations of the medullary tissue are somewhat different, the 

 lymph path here occupying relatively a much greater space than the 

 follicular substance. Moreover, the trabecular system is much less 

 completely developed, and it is not every section of the lymph path 

 which, as in the lymph glands of the ox, is traversed throughout its 

 whole length by a trabecula ; for sometimes the position of the tra- 

 becula is not distinguishable, so that between two neighbouring 

 follicular cords there appears only a homogeneous framework of 

 fibrils ; whilst sometimes closer plexuses are formed by these fibres, 

 which present nodal points analogous to the trabeculse. Lastly, 

 the follicular cords, especially in the lymphatic glands of man, present 

 less sharply defined surfaces towards the lymph path than in the ox, 

 the reticulum is of looser structure, and the lymph corpuscles adhere 

 less firmly ; and thus, by the too firm use of the brush, appearances 

 are easily obtained, of which it is much more difficult to give a satisfac- 

 tory explanation than in preparations obtained from the ox. Lastly, 

 it is to be remarked that the proper lymph tubes penetrate far deeper 

 into the medullary substance. The lymphatic glands of man and the 

 dog, again, differ essentially inter se in this point, that in man a highly 

 developed hilus substance is present, giving a correspondingly distinct 

 reniform shape to the glands, and only absent or sparingly developed 



