EXCRETING ORGANS. 623 



malia, where they are seldom observed in the ulnar or the 

 popliteal regions. These glands are also more compactly 

 united together, and into fewer groups, on the head and 

 neck, and in most parts of the body, in the lower qua- 

 drupeds than in man, as shown by Gurlt in several of 

 the domestic species; this accords with their smaller 

 number of lymphatic absorbents, and of convenient places 

 for their assuming the glandular form. In like manner, 

 where the intestines and mesentery are long, and afford ex- 

 tended space for the distribution of chyliferous vessels, as in 

 herbivora, quadrumana, and man, the mesenteric glands 

 are numerous, small, detached, and spread separately over a 

 large surface ; and where the alimentary canal and mesen- 

 tery are shorter, as in carnivora, these glands are more 

 approximated, aggregated, and often compactly united into 

 the so-named pancreas Assellii. And thus the lymphatic 

 system, though late in its commencement in the animal 

 kingdom, and still mysterious in its function, has advanced 

 by regular and progressive stages to a condition more uni- 

 form in character than the chyliferous, and higher in deve- 

 lopment, by the possession of a rudimentary heart, and has 

 approached the sanguiferous system in the elaboration of its 

 parts, and in its vast distribution through the organs and 

 tissues of the body. 



CHAPTER SEVENTH. 



EXCRETING ORGANS. 



THE residue of the nutrition of all the organs and tissues, 

 and the decayed materials of animal structure, imbibed by 

 the parietes of lymphatics from all points of the body, and 

 conveyed by them to the blood, prepare that fluid to afford 

 the materials of various excretions, to be removed from the 

 system by distinct internal organs or by the general surface 

 of the skin. But animals without lymphatics, and even 

 without blood-vessels, alike possess the means of dissolving 

 and separating from their fabric the old materials which for 



