440 ANATOMICAL AND PATHOLOGICAL OBSERVATIONS. 



external coat. The external tunic of the extra-glandular 

 lymphatics — the afferent and efferent vessels — appears to 

 leave them almost entirely at their entrance and exit from 

 the organ, and by passing on to the surface of the gland forms 

 its capsule. 



This capsule is moderately strong, somewhat smooth on 

 its free, more filamentous on its attached surface, sending in- 

 wards from the latter the processes already described, which 

 not only support the larger branches of the vessels before 

 they anastomose, but also bind together and strengthen the 

 substance of the organ. The larger trunks of the arteries and 

 veins, as they pass through the capsule, and plunge into the 

 substance of the gland, carry along with them also a certain 

 quantity *of filamentous texture, which is derived from the 

 internal surface of the capsule, and is continuous with the 

 processes which surround the larger lymphatic branches. 



The middle or fibrous tunic of the extra-glandular lymph- 

 atics, also begins to disappear after these vessels have pene- 

 trated the capsule of the gland. It is still sufficiently ap- 

 parent on the lymphatics near the surface of the organ, but 

 is met with sparingly towards the centre. Different glands, 

 however, differ in this respect ; the human intra-giandular 

 lymphatics appearing to me to retain more of their fibrous 

 tunic than those in the more granular and developed mesen- 

 teric glands of the dog and seal. 



It is, however, to the changes which the internal tunic of 

 the intra-glandular lymphatics undergoes, that I shall now 

 more particularly direct attention, as these have hitherto 

 escaped observation, and as upon them depend those appear- 

 ances and peculiarities which are yet unexplained. 



I shall first describe the internal tunic, and afterwards its 

 arrangement. 



If this tunic be traced from the afferent lymphatics, in 

 which it presents the usual structure, into the branches im- 



