STItL'CTURE OF LYMI'HATIC GLVNOS. 443 



of this highly-developed portion of the lymi»hatic system of 

 vessels, or, iii other words, the mode in which the afferent 

 communicate with the efferent lymphatics, I have found to 

 coincide with the account usually given of it. The terminal 

 branches of the afferent form a more or less dense network 

 ' with the radicals of the efferent lymphatics. The question 

 which has been so often agitated, as to whether cavities exist, 

 intermediate between the two sets of Ij-mphatics, is not one 

 of much importance. Some lymphatic glands, as has fre- 

 quently been stated, exhibit, after injection with mercuiy, 

 nothing but a mass of lymphatic vessels ; others, again, a 

 mass of apparently intermediate cells ; and Cruikshank cor- 

 rectly remarks, that occasionally, when the mercury first 

 passes through a gland, cells only may appear, but after the 

 injection has been pushed a little further, vessels full of mer- 

 cury may suddenly present themselves. 



These various appearances may be explained by the 

 following facts : — In some lymphatic glands the meshes are 

 elongated, in which case no force short of what is suflRcient 

 to burst the vessels can obliterate the vascular appearance. 

 The intra-glandular lymphatics, like those in other parts, are 

 liable to be over-distended with injections, or by their own 

 contents, so that short vessels or rounded meshes, more 

 especially after great distension, assume the appearance of 

 globular cavities. 



There is another apparently cellular appearance, which is 

 not met with in the human lymphatic glands, but iii some of 

 the lower mammals, which is produced by another cause — the 

 partial or entire obliteration of some of the me.shes, so as to 

 produce cavities more or less extended, with bars or threatls 

 passing from wall to wall, the lymphatics opening into them. 

 This is the conversion of a network of lymphatics into cavities 



* Cruiksliiuik, Thf Anatomy of Ihr Absurbiinj Vrssfls of tht Hinnau Body, 

 page 82. 



