ABSORPTION BY LACTEAL AND LYMPHATIC VESSELS. 311 



lenticular bodies, called lymphatic glands. The number of these glands is very great, al- 



though it is estimated with difficulty, from the fact that many of them are very small and 



are consequently liable to escape obser- 



vation. It may be stated as an approxi- 



mation that there are from six hundred 



to seven hundred lymphatic glands in 



the body. Their size and form are also 



very variable within the limits of health. 



They are generally flattened and len- 



ticular, some as large as a bean, and 



others as small as a small pea or even 



a pin's-head. They are arranged in 



two sets; one superficial, correspond- 



ing with the superficial lymphatic ves- 



sels, and a deep set, corresponding with 



the deep vessels. The superficial glands 



are most numerous in the folds at the 



flexures of the great joints and about 



the great vessels of the head and neck. 



The deep-seated glands are most numer- 



ous around the vessels coming from the 



great glandular viscera. A distinct set 



of large glands is found connected with 



the lymphatic vessels between the 



folds of the mesentery. These are 



known as the mesenteric glands. All 



of the lymphatic vessels pass through 



glands before they arrive at the great 



lymphatic trunks, and most of them 



pass through several glands in their 



rnnrA 



There is some difference of opinion 



, , . , . 



among anatomists concerning the inti- 

 mate structure of the lymphatic glands. Some regard them as composed simply of a 

 plexus of lymphatic vessels, held together by a delicate stroma of fibrous tissue ; while 

 others deny that there is any direct communication between the afferent and the efferent 

 vessels, assuming that the vessels which penetrate the glands break up into small branches 

 which open into a parenchyma filled with closed follicles, and that the fluids are collected 

 from the glands by a second set of capillaries connected with the efferent lymphatics. 

 According to the latter view, the mesenteric glands are little more than collections of 

 follicles like the solitary glands of the intestines, held together by a delicate fibrous 

 structure. This difference of opinion seems to be due to the different methods which 

 have been employed in studying the structure of the glands. Taking, for example, the 

 results arrived at by two prominent investigators, Sappey, who has studied these organs 

 with great success by injections, seems to have clearly demonstrated a lymphatic plexus 

 in their interior, while Kolliker, whose investigations have been confined chiefly to ex- 

 aminations of the organs in a recent state, has not been able to follow out the lymphatic 

 vessels, but has accurately described the contents of the alveoli, or what are regarded by 

 others as closed follicles. In attempting to represent what has been actually demon- 

 strated concerning the structure of these bodies, we shall first take up the appearances 

 which are observed in the fresh structures, and afterward, those points which have been 

 demonstrated by minute injections. 



The perfect, healthy glands are of a grayish-white or reddish color, of about the con- 



FIG. 92. Lymphatics and lymphatic glands. (Sappey.) 

 u PP er extremity of the thoracic duct, passing behind the 

 internal jugular vein ; 2, opening of the thoracic duct into 

 the internal jugular and left subclavian vein. The lym- 

 phatic glands aie seen in the course of the vessels. 



