330 THE LYMPHATIC SYSTEM, BY F. v. RECKLINGHAUSEN. 



that these differences are of a subordinate nature, and that we 

 may now consider a perfectly clear description can be given of 

 all the structural arrangements presented by these glands. 



The lymphatic glands exhibit, not only in different species of 

 animals,but also in one and the same individual, a varying struc- 

 ture which is undoubtedly difficult to define ; the first exami- 

 nation of preparations of the lymphatic glands produces a very 

 confused impression, as may best be understood if it be borne 

 in mind that the variability which in general characterises the 

 lymphatic system manifests itself especially in the structure 

 of these organs. The lymph paths in particular exhibit the 

 greatest variations in form, sometimes being tubular and at 

 others fissure-like or lacuniform, both constantly and for the 

 most part very suddenly passing into each other. 



In the larger and generally also in the smaller lymphatic 

 glands, two substances are distinguishable (Fig. 60), which may 

 be designated the cortical (A), and medullary (B). 



It is true that these names cannot be taken in a strict sense, 

 since if the medullary substance be regarded as occupying a 

 central position surrounded by the cortical substance, we not 

 unfrequently find, on the contrary, considerable portions pre- 

 senting themselves at the surface of the glands, and this else- 

 where than at the bottom of the depression which represents 

 the so-called hilus of the gland, and is occupied with connective 

 tissue, the tissue of the hilus. In the subcutaneous lymphatic 

 glands of the dog, for example, the medullary substance con- 

 stantly appears at the surface, forming spots which may be 

 easily recognised with the naked eye by their white colour, 

 and are frequently separated from the remaining portions of 

 the gland by a yellowish pigmentary border. In these glands 

 no true hilus is present. It cannot be maintained that a sharp 

 distinction exists between the two substances, and we shall 

 hereafter see that there is no essential difference of structure; 

 but that the follicles of the cortex, which are usually regarded 

 as characteristic of it, find their complete analogy in the me- 

 dullary substance. 



Nevertheless it is advantageous, in the first instance, to dis- 

 tinguish between the two substances, since in many animals 

 the difference between them is even macroscopically very per- 



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