ABSORPTION BY LACTEAL AND LYMPHATIC VESSELS. 



305 



hardly perceptible while empty, are capable of being dilated to the diameter of half a line 

 or more, returning to their original size as soon as the distending fluid is removed. 



The peculiarities which the lymphatics present in the different tissues and organs do 

 not possess much physiological interest, except the arrangement of the vessels of origin 

 in the substance of the brain and spinal cord. In the skin, the only interesting peculiarity 

 which we have not already noticed is that the vessels appear to be very unequally dis- 

 tributed in different parts of the surface. According to Sappey, they are particularly 



FIG. 86. Superficial lympJiatics of the arm. 

 (Sappey.) 



FIG. 87. Superficial lymphatics of the leg. 

 (Sappey.) 



abundant in the scalp over the biparietal suture, the soles of the feet and the palms of the 

 hand, the fingers at the lateral portion of the last phalanges, and the scrotum. In the 

 median portion of the scrotum, they attain their highest degree of development. They 

 are also found, though in less number, originating from around the median line on the 

 anterior and posterior surface of the trunk, the posterior median portion of the extremi- 

 ties, the skin over the mammaa, and around the orifices of the mucous passages. Sappey 

 has injected lymphatic vessels in the anterior portion of the forearm, the thigh, and the 

 leg, and the middle portion of the face, although they are demonstrated with difficulty in 

 these situations. If they exist at all in other portions of the cutaneous surface, they are 

 not numerous and are rudimentary 

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