CHAPTER XXIII. 

 THE LYMPHATIC SYSTEM AND THE DUCTLESS GLANDS. 



The Lymphatics or Absorbents are very widely distrib- 

 uted in the Body. Most organs, as has been pointed 

 out (p. 63), possess a sort of internal skeleton made up 

 of connective tissue, which consists mainly of bundles of 

 fibres, united together and covered-in by a " cement" sub- 

 stance. In this substance are found numerous cavities, usu- 

 ally branched, and communicating with one another by their 

 branches. They frequently contain connective-tissue cor- 

 puscles, which, however, do not completely fill them; and 

 they thus, with their branches, form a set of intercommuni- 

 cating channels known as the " lymph-canaliculi" because 

 they are filled with lymph. As the connective tissues accom- 

 pany blood-vessels wherever the latter run, the canaliculi, 

 which are frequently relatively large around the blood-capil- 

 laries, take up the liquid which transudes through their walls, 

 and this transudation liquid is the origin of the lymph. 

 Even where blood-vessels and connective tissue do not pene- 

 trate, as in bone between the Haversian canals, lymph-canal- 

 iculi penetrate, being connected with the cavities in which 

 the bone-corpuscles lie; and in the deeper layers of the 

 epidermis the cells are covered with prickle-like projections 

 and unite by the tips of these so as to leave minute channels 

 which apparently are lymph-canaliculi. These very minute 

 channels, with no definite lining cells, but mere crevices be- 

 tween tissue elements, or tubes hollowed out in the matrix of 

 connective tissue, bone and (possibly) cartilage, constitute 

 the origin of the lymphatic system. The transudation liquid 

 which enters them from the blood-vessels is rapidly altered 

 by interchange with the neighboring tissues, losing certain 

 materials and gathering others; and as the substances taken 

 and the waste and other products returned vary very much 

 in different organs, the lymph leaving them must differ also. 

 Nevertheless it retains certain common features, histological 



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