THE LYMPHATICS. 319 



not apply to all cases. In Man, and in other animals, there are 

 small and smallest glands, of 3'" — &'" — 1'", or even J"', in which 

 the interior does not distinctly exhibit the alveolar structure, 

 appearing, on the contrary, to be more continuous throughout, 

 and homogeneous, notwithstanding a good many traces of 

 fibrous structure, which always exist even in them. In the larger 

 glands also, especially in certain animals, a similar condition 

 of the contents is not unfrequently presented, which of course 

 does not materially affect the above exposition of the structure 

 of the lymphatic glands, since, in such cases, we simply see a 

 less developed condition of the septa, and a more intimate 

 union of the individual parts of the pulp. 



O. Heyfelder has lately described (1. c), in the lymphatic 

 glands of the Mouse, the Rat, and, to some extent, of the 

 Rabbit, a complete muscular layer. In the Bat also, the Dog, 

 Sheep, Ox, Goose, and Fowl, smooth muscles are said to occur 

 sparingly, and to be fewest in Man. Heyfelder also says that 

 they pass into the internal septa, and that in the Rabbit he has 

 noticed contractions of the glands upon electrical excitement, 

 an experiment which has not yet succeeded with me. 



The lymphatic glands are subject to numerous degenerations. 

 The most frequent are extravasations of blood in the alveoli, 

 and in consequence of these effusions, depositions of pigmentary 

 matter, which may proceed to such an extent as to render the 

 glands brownish-red, or even black (bronchial-glands) ; we also 

 find thickenings of the sheath, and of the internal septa ; fatty 

 deposits in the blood-vessels; hypertrophies, with a uniform 

 increase of all their parts ; tuberculosis and cancer. ,] l 



1 [Professor Brucke, in a valuable communication read before the Vienna Academy, 

 March 31, 1853 (' Ueber die Chylus-gefasse und die Fortbewegung der Chylus'), con- 

 firms the account given by Ludwig and Noll of the structure of the lymphatic 

 glands, and states that the vasa inferentia break up into the porous, glandular tissue, 

 out of which the vasa efferentia arise anew. In the glands themselves, a distinction 

 must be drawn between the cortical substance, composed of round or ovate bodies, 

 like the separate glandular bodies of Peyer's patches, and the medullary substance. 

 The framework of the latter is formed by the large blood-vessels, with their tunica 

 adventitice. One portion of their branches divides into capillaries in the medullary 

 substance, the rest enter the cortical substance. The accompanying connective tissue 

 becomes looser, the finer the branches. The fully developed connective fibres disap- 

 pear more and more, and in their place cytoblasts appear, with closely investing cell- 

 membranes, which run out into two or three pointed, sometimes flat, usually filiform 



