LYMPHATIC GLANDS. 119 



The tubes of the second variety, instead of dividing 

 like the branches of a tree, scarcely ramify at all, but 

 proceed on in their course with scarcely any change in their 

 diameter, as in the kidneys and testicles. Here we find 

 the tubes convoluted and of extraordinary length, measuring 

 in the testicle, according to Dr. Munroe, 5208 feet 



The celebrated Kuysch, from his very minute injections, 

 was led to believe that glands consisted entirely of blood 

 vessels, which had a direct communication with the excre- 

 tory duct But more recent observations, says Muller, 

 show " that the secreting canals in all glands, form an in- 

 dependent system of tubes that whether they be convo- 

 luted as in the kidney and testes, or ramified in an arbor- 

 escent form, as in the liver and salivary glands ; whether 

 they terminate by twig-like cceca, as in the liver, or in 

 grape-like clusters of cells, as in the salivary glands, pan- 

 creas, and mammary gland ; their only connection with the 

 blood vessels, in all cases, consists in the latter ramifying 

 and forming a capillary net work on their walls, and in 

 their interstices, 'and that the finest secreting tubes are 

 always several times larger in diameter than the minute 

 ramifications of the arteries and veins." 



The lungs, it is supposed, furnish the best type for the 

 whole series of glandular organs. 



The general conclusion to which the microscope has led, 

 in reference to the structure of glands, is, that the primi- 

 tive cell is the fundamental and operative part in which all 

 secretion occurs, whether in the simple or complex gland, 

 or in the lengthened secreting tubes, or in the skin or any 

 of the membranes of the body ; and that however various 

 the form of the elementary parts, all the glands, without 

 exception, which secrete a fluid, follow the same law of 

 conformation, by developing themselves from the simple 

 follicle. 



LYMPHATIC GLANDS. 



Under this head we will give a general description of 

 the absorbent system, which is as important and interest- 

 ing as the sanguineous. If the latter carries into the 



